1 CdTe solar cells Master in Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali Francesco Biccari
2 Cadmium telluride (CdTe) Chalcogenide semiconductor Zincblend structure Direct energy gap 1.44 ev Can be growth both p-type (V Cd acceptors) or n-type (Cd i donors) m e = 0.1 m 0 µ e = 1100 cm 2 /Vs in single crystals Difficult extrinsic doping η th = 31% Source: Wikipedia Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 2/39
3 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 3/39 CdTe solar cells. Brief history CdTe based solar cells are studied since pn-homounction, both poly- and single-crystal give poor efficiency (3%) 1960: n-cds/p-cdte, 1972: Bonnet and Rabenhorst obtain 6% efficiency 1981: Kodak introduces Close Spaced Sublimation method 1991: Ting L. Chu introduces a front window layer reducing the thickness of CdS 15% efficiency! Born of Solar Cell Incorporated (now First Solar) 2002: NREL obtains 16.5% efficiency (current world record) 2005: First Solar reaches 25 MWp/y of production 2009: EMPA Labs show 13.5% efficiency on flexible polyimide substrates 2010: First Solar production cost: 0.75 /Wp! Capacity 1.5 GWp/y!
4 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 4/39 CdTe solar cells. Superstrate The superstrate configuration is used in most CdTe solar cells This is due to the particular difficulty in making the rear contact (we will see why) The back contact is usually deposited at the end of the cell to have a better control Superstrate configuration!
5 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 5/39 TCO The free carrier absorption in the infrared is less important for CdTe because of its higher gap with respect to, for example, CIGSe or CISe. The window layer is usually divided in two layers: a highly conductive and thick TCO and a diffusion barrier between the first TCO and CdS. Record NREL cell: borosilicate glass/cd 2 SnO 4 /Zn 2 SnO 4 /CdS/CdTe/metal Typical cell: glass/ito/sno 2 /CdS/CdTe/metal or FTO instead of ITO In principle AZO is cheaper than ITO. But AZO degrades during the other steps (especially CdCl 2 ) giving a high series resistance
6 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 6/39 CdS CdS is a semiconductor with E g = 2.42 ev. It is yellow! It should be a window layer but it should be as thin as possible (we will see why) and it is called buffer layer. Deposition methods: Evaporation Sputtering Close Spaced Sublimation (CSS) Vapour Transient Deposition (VTD) Chemical Vapour Deposition (CVD) Chemical Bath Deposition (CBD) CdS Glass TCO CdTe Mo
7 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 7/39 CdS Compact to reduce shunts It can suffer from the subsequent processes (in superstrate configuration) Lattice mismatch with the absorber: defects Partecipation to carrier collection? Probably no High absorption in blue: usage of a TCO as window layer. CdS very thin! High resistance: usage of a TCO as window layer. CdS very thin! Poortmans
8 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 8/39 CdS deposited by CBD or VTD Chemical Bath deposition (CBD) is not used for CdTe Cd 2+ source (CdSO 4, CdI 2 ) + NH 3 + S 2- source (thiourea) + H 2 O T = 70 C, reaction of Cd 2+ with S 2- to form CdS First Solar uses Vapor Transport Deposition (VTD) where the CdS is evaporated in an inert atmosphere and carried toward the glass with an inert gas flux (The same technique is used for CdTe, see below)
9 CdS effects. CdS/CdTe interdiffusion CdS/CdTe: ~10% lattice mismatch and different crystal structures (wurtzite CdS vs zincblend CdTe) However the junction shows good electronic properties! The explanation is the possibility of CdTe and CdS to mix. A sulfur rich CdTe phase, CdTe 1 x S x, in the CdTe absorber, and a tellurium rich CdS phase, CdS 1 y Te y, in the CdS layer. The bandgap E g (x) of the mixed phases has a minimum value 1.40 ev at a composition of around 25% (atomic) CdS in CdTe. This effect shifts the QE of CdTe/CdS cells to longer wavelengths with a few tens of nm. Around λ = 520 nm, the CdS 1 y Te y in CdS enhances the absorption (this is a loss) Around λ = 860 nm, the CdTe 1 x S x in CdTe enhances the absorption (this is a gain) Normally, the gain in the infrared does not compensate for the loss in the green region Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 9/39
10 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 10/39 CdTe deposition techniques Close Spaced Sublimation (CSS). High temperatures, up to 650 C, give the best cells but borosilicate glass is needed. High cost. Commercial scale systems use soda lime glass (550 C). (Antec Solar, Mitsubishi). Vapor Transport Deposition (VTD). Low temperatures. Very fast. (First Solar) PVD, MOCVD, sputtering. Intermediate temperatures: 250 C to 350 C. Electrodeposition. At about 90 C. All of these methods have yielded cells with performance well above 10%. Why CdTe has this unparalleled flexibility? Great stability of the binary compound with a tendency to self compensate with intrinsic defects to form quite stable p-type CdTe. Use of post-deposition activation treatments which involves an anneal step at 400 C in the presence of some O 2 and Cl.
11 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 11/39 CdTe: Phase diagram CdTe(s)+Cd(s) CdTe(s)+Te(s) CdTe is the only stable compound in the phase diagram!
12 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 12/39 CdTe. Self stabilization Equilibrium vapor pressure of elemental Cd and Te is much higher than that of CdTe: therefore the pure phases tend to re-evaporate 2 CdTe (s) 2 Cd (g) + Te 2 (g) Log(p Te2 (atm))= /T Low temperature congruent sublimation. The composition is self stabilizing.
13 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 13/39 CdTe. Close Spaced Sublimation The driving force for the deposition is the temperature difference Substrates and sources are very close together. The film growth occurs close to equilibrium condition. This small difference in temperature limits the deposition rate In rough vacuum or in inert gas For CdTe and CdS (600 C) (700 C) Deposition rate: 1 µm/min!
14 CdTe. Vapor Transport Deposition Similar to CSS but the source and the substrate environments are decoupled: the temperature difference can be larger! Industrially simpler Deposition rate: Up to 1 µm/s! P 1 = P 2 + cost Φ He Limited by surface kinetics (sticking coefficient) Limited by dilution of the source Kestner (2004) Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 14/39
15 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 15/39 VTD. First Solar and NREL The key enabler for low-cost, high-throughput manufacture is rapid deposition of high-quality semiconductor films
16 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 16/39 CdTe. Intrinsic defects CdTe is a ionic material with a large interatomic distance and low cohesive strength. The vacancy formation energy is therefore low. Te = Te = Te = Te = Te = Te = Cd ++ Cd ++ Cd ++ Te = Te = Te = Te = Te = Cd ++ Te = Cd ++ Cd ++ Cd ++ Cd ++ Te = Te = Te = Te = Te = Te = Cd Vacancy (V Cd, acceptor) Cd Interstitial (Cd i, donor) For PV application p-type CdTe is preferred. The density of cadmium vacancies is in the range of to cm -3 for a typical PV material.
17 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 17/39 CdTe: intrinsic defects and dopants Copper in CdTe is an acceptor (it sits on a cadmium site: Cu Cd ) Poortmans (2006) Chlorine resides on a tellurium site (Cl Te ), acts as a shallow donor. It forms, however, a complex with a doubly negatively charged cadmium vacancy, and this negatively charged (Cl + Te V 2 Cd ) complex acts as a single acceptor.
18 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 18/39 CdTe. The magic CdCl 2 treatment CdCl 2 treatment of CdTe (called post-deposition treatment) is fundamental to obtain good solar cells. Presence of oxygen is beneficial. Increased grain size in CdTe and in CdS when the initial grains are small (not with CSS and VTD). Grain growth, which can occur during CdCl 2 treatment, introduces stress at the interface between the CdS and TCO layer, resulting in film blistering or peeling. (Cl solubility in CdTe is low: diffusion along the grain boundaries with the formation of CdO and TeCl 2 ) Subgrains disappear, grain-boundary passivation p-type doping Passivation of recombination defects: longer minority carriers lifetimes. Interaction with Cl, O and V Cd can however generate other deep defects Increased CdS/CdTe interface alloying: reduced lattice mismatch between the CdS and CdTe layers CdCl 2 overtreatment can result in adhesion loss problems, deep defects formation
19 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 19/39 CdTe. Post deposition treatment Solution of methanol and CdCl 2 sprayed on CdTe and subsequentely heated at 450 C for few minutes CdCl 2 thin film over CdTe applied by evaporation, CSS or VTD Other methods (gaseous CdCl 2 ) or other compound containing Cl (HCl, NaCl, ) are under study CdCl 2 is highly toxic and soluble in water and alcohol!
20 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 20/39 Back contact problems CdTe is a material with high electron affinity (χ = 4.28 ev) A metal with a high work function is needed (only noble metals! Φ Au = 5.4 ev and Φ Pt = 5.7 ev). Ideal theory! Fermi level pinning! Poortmans (2006)
21 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 21/39 Back contact problems The strategy is to form a highly doped p + region at the CdTe back contact in order to permit the tunnelling of the holes. But CdTe extrinsic doping is not simple (autocompensation). The p + region is obtained by etching (C 2 H 5 BrO, HNO 3 :H 3 PO 4, etc ) the back surface of CdTe leaving a Te-rich layer. Etching can introduce shunt paths due to preferential etching at grain boundaries Most commonly used back-contact materials are: Cu based: Cu:Au, ZnTe:Cu, Cu x Te:HgTe/graphite, Cu/graphite, HgTe:Cu/graphite paste/ag paste (record cell) Copper is used because of its acceptor character (when introduced in larger quantities, however, part of the copper will occupy an interstitial place, and this Cu i acts as a donor!) Moreover Cu decreases lifetime of minority carries Cu free: Ni-P, Sb 2 Te 3 /Mo, HgTe/graphite, Ni/Al, Sb/Mo
22 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 22/39 Effects of Cu from the back contact Unfortunately copper can diffuse D Cu in CdTe = 3.7 x 10-4 exp (-0.67 ev/kt) If Cu diffusion is insufficient, the entire CdTe layer is depleted if Cu diffusion is excessive: the depletion width can become too narrow Cu may segregate into the grain boundaries forming shunting paths Cu can arrive to CdS increasing its resistivity The Cu diffusion and therefore the degradation is accelerated by temperature and illumination Most contact processes used for CdS/CdTe devices are optimized (often unknowingly) to result in an optimal depletion width
23 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 23/39 CdTe modules Manufacturing Capacity in 2009: First Solar (USA): 1100 MW/yr Calyxo (Q-cells DEU): 25 MW/yr Antec Solar (DE): 10 MW/yr PrimeStar Solar Arendi (Italia) First Solar is the first company for production capacity in Roth& Rau has announced in February 2009 that it will be able, by the end of the year, to sell complete production lines for CdTe Modules. 12% efficiency
24 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 24/39 First Solar 40 MW solar field installed in Germany (First Solar). Completed in December Estimated total price 130 M (3.25 /W). It is one of the largest solar fields in the world and also one with a low price. First solar production lines: Malaysia (1.5 GWp) Germany (0.5 GWp) USA (0.25 GWp) France (0.1 GWp)
25 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 25/39 First Solar process (in 2000) Substrate cleaning APCVD SnO 2 undoped VTD CdS VTD CdTe (3 µm) CdCl 2 treatment Cu x Te formation Sputtering Back contact Laser scribing Laser scribing Laser scribing High throughput: 1 module 120 cm x 60 cm in 15 s, 17 kwp/h, 100 MWp/year for 3 shifts Doped SnO 2 (ITO) coated soda lime glass substrate Undoped SnO 2 deposition by APCVD and buffer layer (CdS) by VTD CdCl 2 aqueous solution is sprayed on the CdTe formed on the glass substrate, and subsequently treated in a belt furnace First Solar process to make the back ohmic contact while reducing the Cu available: A chemical etch of CdTe to create a Te-rich surface Deposition of only 2 nm of Cu Annealing to form the compound Cu x Te (a good p-type semiconductor) Sputtering of metal for the back contact
26 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 26/39 First Solar CdTe module stability Tucson Electric/First Solar 480 kw thin film CdTe solar field installed in 2003
27 First Solar. Module cost per Wp 2009 december. Manufacturing module cost 0.84 $/Wp 2012 december: target of 0.7 $/Wp! targer of BOS, 1 $/Wp! $/W Last update: 2011 Module cost (2002 $/Wp) 10 1 a-si modules CdTe modules FOSSIL FUEL COMPETITIVE LEVEL $/W 2005 c-si shortage c-si modules 81% learning curve Grid parity at our latitudes is near! 0.1 1E Cumulative production (GWp) Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 27/39
28 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 28/39 CdTe solar cells. Matsushita process Borosilicate glass is used as a substrate. Spray pyrolysis for SnO 2 :F film (500 nm, ρ sheet <10Ωsq). Spray pyrolysis for CdS (100 nm). Close Spaced sublimation for CdTe film (3 7 µm) 0.3M CdCl 2 aqueous solution is sprayed on the CdTe formed on the glass substrate, and subsequently treated in a belt furnace at 420 C for 30 min in air. After the heat treatment, the substrate is rinsed in de-ionized water, and dried in an N 2 atmosphere. Sandblast technique to pattern the CdTe film. Screen printing of Carbon paste (containing Cu and/or Pb) for the ohmic contact. Screen printing of Ag paint as a metal electrode.
29 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 29/39 Arendi. Italian CdTe solar modules Glass cleaning Front TCO Sputtering CdS sputtering With CHF 3 CSS CdTe (Ar+O 2 ) CHF 3 Cl treatment Sputtering As 2 Te 3 /Cu/Mo Laser scribing Laser scribing Laser scribing 400 ºC 250 ºC 500 ºC 400 ºC 300 ºC RT RT RT RT Improvements: 1.New deposition process for the CdS: sputtering in Ar + CHF 3 (better reproducibility) 2.Substitution of the CdCl 2 step by treating CdTe films at 400 C, for a few minutes in an atmosphere containing HCFCl 2, (a Freon which is non toxic and inert at room temperature): no risk of stocking CdCl 2, faster process 3.Elimination of the acid etch of the CdTe surface. 4. Back contact: deposition on top of a not etched surface of nm of As 2 Te 3 followed by the deposition of 10-20nm of Cu at C. A reaction between Cu and As 2 Te 3 happens forming a Cu x Te layer by a substitution reaction. This type of contact resulted to be stable and non rectifying.
30 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 30/39 CdTe modules. Roth&Rau turnkey line Roth & Rau has recently completed the development of the first CdTe turnkey production line. Nominal capacity: 80 MWp (glass-glass modules 1.2 m x 1.6 m) Targets: Conversion efficiency at 10%, production yield of 95%, production cost less than 1 /Wp
31 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 31/39 CdTe Roth & Rau turnkey line Production steps for CdTe modules 1. CdTe deposition 2. Activation 3. Back contact sputtering 4. Encapsulation
32 CdTe. Environmental issues Elemental cadmium is highly toxic. Detrimental effects on kidney and bone. Carcinogen for lungs. High energies of the CdTe and the CdS bonds, extremely low water solubility and the low vapor pressure of CdTe and CdS. CdTe and CdS are not so toxic! A 1 m 2 solar module contains about 6 g of Cd in CdTe and CdS. A typical AA Ni-Cd battery contains 4 g of metal Cd! Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 32/39
33 CdTe. Environmental issues Mining and production of CdTe and CdS Safe Production of solar modules Safe, deep studies from NREL, First Solar and Antec Active life of solar modules CdTe melts at 1041 C, CdS melts at 1750 C The modules are completely safe during normal operation and even during a fire the thin layers of CdTe and CdS would be encapsulated inside the molten glass, so any Cd vapor emissions are unlikely Dismantling, disposal and recycling of modules Even cracking a module does not produce any relevant Cd contamination. Specifically recycling programs from all companies Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 33/39
34 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 34/39 Temperature coefficient With the increasing temperature, j sc sligthly increases while V oc decreases V V oc oc ( T 0 + dt ) ( T0 + dt ) V ( T ) oc 0 V oc 1+ ( T 0 dt dvoc ( T ) ) + dt dt V oc 1 ( T 0 ) T 0 dvoc ( T ) dt T 0 1+ β ( E g ) dt V oc temperature coefficient β 1 T 0 E g C C with E g > C Try to demonstrate this expression valid for an ideal solar cell. Approx. E g >> kt 0, j sc >> j S The higher the band gap the lower the temperature coefficient First solar module: β = %/ C. Same percentage for efficiency. For c-si modules: β = - 0.5%/ C
35 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 35/39 Materials availability: a future problem? Indium requirement: 0.03 gr/wp: the price is still acceptable The entire In production would give a maximum of 10 GWp/yr PV production. J.J. Scragg et al, Phys. stat. sol. (b) 245, 1772 (2008)
36 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 36/39 Materials availability: a future problem? Modules (Eff 10%) Metal Required (g/m 2 ) Reserves 1998 (Gg) Production 1999 (Gg/yr) Limit power (TWp) 1999 limit annual prod (GWp/yr) 2020 limit annual prod (GWp/yr) CdTe (2 µm) Cd Te CIGS (2 µm) Se Ga In asige (0.2 µm) Ge Dye Ru Source: B. A. Andersson, Prog. Photovolt. Res. Appl. 8, 61 (2000) Total PV 2010 production 27 GWp (2 GWp due to CdTe and CIGS) No availability problems in the next 5-10 years On the long term availability problems for In and Te could arise. (10 5 TWh 2006 world consumption: 10 TWp of PV) 11 20
37 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 37/39 CdTe solar cells. Conclusions (1) High efficiency The polycrystalline nature of the thin film is not detrimental and poly thin film solar cells give higher efficiency compared to their single crystal counterparts Stability The polycrystalline nature tolerate quite high concentration of impurities Even if some problems could exist with the diffusion of Cu, First Solar modules show a very good stability Low cost Effective use of raw materials Small energy pay-back time (less than two years) No doping: the p-type conductivity due to intrinsic defects is used Adaptable to various applications
38 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 38/39 CdTe solar cells. Conclusions (2) CIGSe modules have reached 1.44 GWp of production in 2010! CdTe cost per Wp is similar or lower than a-si but CdTe efficiency is higher! At the moment the main product type is a glass monolithic module but probably a large production increase will derive from the introduction of flexible modules. Materials availability is not going to be a big problem in the next years and it will improve in response to demand and price increase. Environmental and safety problems are manageable in the production phase and almost irrelevant for the user.
39 Francesco Biccari Master Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali 39/39 Acknowledgments Thanks to Dr. Alberto Mittiga for providing several figures, numbers and slides of this presentation Thanks to Dr. Rosa Chierchia for useful discussions Thanks to Dr. Shenjiang Xia for pointing me out some mistakes
CuIn 1-x Ga x Se 2 solar cells Master in Ingegneria del Fotovoltaico Corso di Tecnologie Fotovoltaiche Convenzionali Francesco Biccari firstname.lastname@example.org 2012-04-25 Francesco Biccari Master Ingegneria del
Polysilicon Renewable Energy Corporation L. Carnel Scanwafer Wafers Cells Modules HIT = Heterojunction with Intrinsic Thin-layer : first used by Sanyo in 1992 and now used for high-efficiency solar cells
Foundations of photovoltaics: II. the photovoltaic effect, materials for applications Maria L. Calvo Department of Optics Faculty of Physical Sciences Complutense University of Madrid, Spain Outline of
1 Photovoltaics Photovoltaic (PV) materials and devices convert sunlight into electrical energy, and PV cells are commonly known as solar cells. Photovoltaics can literally be translated as light-electricity.
PHOTOVOLTAIC'S TECHNOLOGY OVERVIEW Associated Professor, Mechanical Engineering Department Frederick University. 29-30 May 2014 Aphrodite Hills Hotel, Paphos IRENA CYPRUS EVENT CONTENTS Available Technologies
CMOS Processing Technology Silicon: a semiconductor with resistance between that of conductor and an insulator. Conductivity of silicon can be changed several orders of magnitude by introducing impurity
1 Layer Deposition: Thermal Oxidation and CVD Rupesh Gupta IIT Delhi Supervisor: Dr. Chacko Jacob 2 OUTLINE Thermal Oxidation and Model o Factors Affecting Kinetics o Future Trends: Oxidation o CVD and
Solar Photovoltaic (PV) Cells A supplement topic to: Mi ti l S Micro-optical Sensors - A MEMS for electric power generation Science of Silicon PV Cells Scientific base for solar PV electric power generation
SOLAR ELECTRICITY: PROBLEM, CONSTRAINTS AND SOLUTIONS The United States generates over 4,110 TWh of electricity each year, costing $400 billion and emitting 2.5 billion metric tons of carbon dioxide (Yildiz,
Lecture 19: Solar cells Contents 1 Introduction 1 2 Solar spectrum 2 3 Solar cell working principle 3 4 Solar cell I-V characteristics 7 5 Solar cell materials and efficiency 10 1 Introduction Solar cells
4.1 SOLAR CELL OPERATION Y. Baghzouz ECE Department UNLV SOLAR CELL STRUCTURE Light shining on the solar cell produces both a current and a voltage to generate electric power. This process requires a material
Nanoparticle Enhanced Thin Film Solar Cells Solar Cells Solar cells convert visible light to electricity. It is one of the clean sources of energy. In theory a 100 square mile area covered with solar panels
Lasers in Solar Manufacturing The Cutting-Edge of Green Solar Panel Production Superior Reliability & Performance P1 (below) and P3 (right) layer patterning in a-si thin-film panels Talisker and Paladin
Light management for photovoltaics Ando Kuypers, TNO Program manager Solar Global energy consumption: 500 ExaJoule/Year Solar irradiation on earth sphere: 5.000.000 ExaJoule/year 2 Capturing 0,01% covers
Thin Is In, But Not Too Thin! K.V. Ravi Crystal Solar, Inc. Abstract The trade-off between thick (~170 microns) silicon-based PV and thin (a few microns) film non-silicon and amorphous silicon PV is addressed
Photovoltaic Power: Science and Technology Fundamentals Bob Clark-Phelps, Ph.D. Evergreen Solar, Inc. Renewable Energy Seminar, Nov. 2, 2006 Photovoltaic Principle Energy Conduction Band electron Energy
High Open Circuit Voltage of MQW Amorphous Silicon Photovoltaic Structures ARGYRIOS C. VARONIDES Physics and EE Department University of Scranton 800 Linden Street, Scranton PA, 18510 United States Abstract:
Module 6 : PHYSICS OF SEMICONDUCTOR DEVICES Lecture 34 : Intrinsic Semiconductors Objectives In this course you will learn the following Intrinsic and extrinsic semiconductors. Fermi level in a semiconductor.
Chapter 5 5.6 Doped GaAs Consider the GaAs crystal at 300 K. a. Calculate the intrinsic conductivity and resistivity. Second Edition ( 2001 McGraw-Hill) b. In a sample containing only 10 15 cm -3 ionized
New materials for Mirjam Theelen 2 A little bit about myself Born in Eindhoven 2001-2007 Study chemistry in Nijmegen Solid State Chemistry Physical Chemistry 2007-present Scientist at TNO (Eindhoven) Research
Semiconductors, diodes, transistors (Horst Wahl, QuarkNet presentation, June 2001) Electrical conductivity! Energy bands in solids! Band structure and conductivity Semiconductors! Intrinsic semiconductors!
Lecture 12 Physical Vapor Deposition: Evaporation and Sputtering Reading: Chapter 12 Evaporation and Sputtering (Metalization) Evaporation For all devices, there is a need to go from semiconductor to metal.
The fabrication of a monolithic transistor includes the following steps. 1. Epitaxial growth 2. Oxidation 3. Photolithography 4. Isolation diffusion 5. Base diffusion 6. Emitter diffusion 7. Contact mask
Processing of Semiconducting Materials Prof. Pallab Banner Department of Material Science Indian Institute of Technology, Kharagpur Lecture - 40 Materials for Photovoltaics This is the last topic in this
Applied Quantum Mechanics for Electrical Engineers Workshop II Energy Band Model and Doping 95 pts Objective: Explore the effect of doping on the energy band diagram and the carrier concentration. Instructions:
Doped Semiconductors Dr. Katarzyna Skorupska 1 Doped semiconductors Increasing the conductivity of semiconductors by incorporation of foreign atoms requires increase of the concentration of mobile charge
ELG4126: Photovoltaic Materials Based Partially on Renewable and Efficient Electric Power System, Gilbert M. Masters, Wiely Introduction A material or device that is capable of converting the energy contained
Blue Lasers Photonics and Optical Communications Zubin Advantages of blue lasers and Blue (GaN) LEDs are around 100 times brighter than conventional LEDs More efficient (energy-wise) than light bulbs Longer
THE WAY TO SOMEWHERE Sub-topics 1 Diffusion Diffusion processes in industry RATE PROCESSES IN SOLIDS At any temperature different from absolute zero all atoms, irrespective of their state of aggregation
University of California at Santa Cruz Jack Baskin School of Engineering Electrical Engineering Department EE-145L: Properties of Materials Laboratory Lab 7: Solar Cells Spring 2002 Dawn Hettelsater, Yan
Epitaxy Epitaxial Growth Epitaxy means the growth of a single crystal film on top of a crystalline substrate. For most thin film applications (hard and soft coatings, optical coatings, protective coatings)
Mar. 9, 2010 Due Mar. 29, 2010 3.003 Lab 4 Simulation of Solar Cells Objective: To design a silicon solar cell by simulation. The design parameters to be varied in this lab are doping levels of the substrate
Analog & Digital Electronics Course No: PH-218 Lecture 1: Semiconductor Materials Course Instructors: Dr. A. P. VAJPEYI Department of Physics, Indian Institute of Technology Guwahati, India 1 Semiconductors
production Systems For Touch Panel and LCD Sputtering/PECVD/ Wet Processing Pilot and Production Systems Process Solutions with over 20 Years of Know-how Process Technology at a Glance for Touch Panel,
The Current status of Korean silicon photovoltaic industry and market 2011. 3.17 Sangwook Park LG Electronics Inc. contents 1.Introduction (World PV Market) 2.Korean PV market 3.Photovoltaics in LG Electronics
Physics 610/Chemistry 678 Semiconductor Processing and Characterization Quiz I July 18, 2014 Part I: Short-answer questions on basic principles. (5 points each) 1. Briefly describe the CZ method and the
MOCVD growth system General MOCVD growth features Advantages Faster growth than MBE, can be a few microns per hour; multi-wafer capability easily achievable Higher temperature growth; growth process is
VLSI Technology Dr. Nandita Dasgupta Department of Electrical Engineering Indian Institute of Technology, Madras Lecture - 14 Oxidation IV Oxide Charges and Oxidation Systems So, in the last class we were
Solid State Detectors = Semi-Conductor based Detectors Materials and their properties Energy bands and electronic structure Charge transport and conductivity Boundaries: the p-n junction Charge collection
Condensed Matter Physics Prof. G. Rangarajan Department of Physics Indian Institute of Technology, Madras Lecture - 36 Semiconductors We will start a discussion of semiconductors one of the most important
Semiconductor doping Si solar Cell Two Levels of Masks - photoresist, alignment Etch and oxidation to isolate thermal oxide, deposited oxide, wet etching, dry etching, isolation schemes Doping - diffusion/ion
Crystalline solids A solid crystal consists of different atoms arranged in a periodic structure. Crystals can be formed via various bonding mechanisms: Ionic bonding Covalent bonding Metallic bonding Van
The Physics of Energy sources Renewable sources of energy Solar Energy B. Maffei Bruno.email@example.com Renewable sources 1 Solar power! There are basically two ways of using directly the radiative
Silicon Wafer Solar Cells Armin Aberle Solar Energy Research Institute of Singapore (SERIS) National University of Singapore (NUS) April 2009 1 1. PV Some background Photovoltaics (PV): Direct conversion
Italian National Agency for New Technologies, Energy and Sustainable Economic Development Materials and Technologies for Renewable Energy ENEA R&D activities on PV Anna De Lillo ENEA UTT-RINN Castel Romano,
F. G. Tseng Lec6, Fall/2001, p1 Lecture 6 PVD (Physical vapor deposition): Evaporation and Sputtering Vacuum evaporation 1. Fundamental of Evaporation: The material to be evaporated is heated in an evacuated
MTE 585 Oxidation of Materials Part 1 Ref. Ch. 11 in Superalloys II Ch. 8 in Khanna Ch. 14 in Tien & Caulfield Introduction To illustrate the case of high temperature oxidation, we will use Ni-base superalloys.
Fundamentals of Photovoltaic Materials National Solar Power Reasearch Institute, Inc. 12/21/98-1 - 12/21/98 Introduction Photovoltaics (PV) comprises the technology to convert sunlight directly into electricity.
MMIC Design and Technology Fabrication of MMIC Instructor Dr. Ali Medi Substrate Process Choice Mobility & Peak Velocity: Frequency Response Band-Gap Energy: Breakdown Voltage (Power-Handling) Resistivity:
Designing of Amorphous Silicon Solar Cells for Optimal Photovoltaic Performance Latchiraju Pericherla A Thesis submitted in part fulfilment of the requirements for the degree of Master of Engineering School
contamination analysis for compound semiconductors ANALYTICAL SERVICES B u r i e d d e f e c t s, E v a n s A n a l y t i c a l g r o u p h e l p s y o u C O N T R O L C O N T A M I N A T I O N Contamination
10p PhD Course Semiconductor Physics 18 Lectures Nov-Dec 2011 and Jan Feb 2012 Literature Semiconductor Physics K. Seeger The Physics of Semiconductors Grundmann Basic Semiconductors Physics - Hamaguchi
Diode Applications This chapter teaches the employment of pn-junction diodes in various applications. Rectifier diodes Rectifier diodes are used, for example, in power supplies, AC-to-DC converters, and
From Nano-Electronics and Photonics to Renewable Energy Tom Smy Department of Electronics, Carleton University Questions are welcome! OUTLINE Introduction: to EE and Engineering Physics Renewable Energy
Searching New Materials for Energy Conversion and Energy Storage ZÜRICH & COLLEGIU UM HELVE ETICUM R. NES SPER ETH 1. Renewable Energy 2. Solar Cells 3. Thermoelectricity 4. Fast High Energy Li-Ion Batteries
INTRODUCTION TO ELECTRONIC DEVICES MENJANA MINDA KREATIF DAN INOVATIF Introduction What is Electronics? Electronic Devices? Electronic Systems? introduction Electronics: The branch of physics that deals
OPTIMIZE SOLAR CELL PERFORMANCE D R A G I C A V A S I L E S K A MINIMIZE LOSSES IN SOLAR CELLS Optical loss Concentration of light Minimize Shadowing Trapping of light: AR coatings Mirrors ( metallization
AIMCAL Conference 30 May 2 June 2016 Dresden Germany Eritt, Michael Heliatek GmbH Challenges of vacuum roll-to-roll processing of organic solar cells and encapsulation processes Heliatek uses an efficient
1 P a g e Physics Notes Class 12 Chapter 14 Semiconductor Electronics, Materials, Devices and Sample Circuits It is the branch of science which deals with the electron flow through a vacuum, gas or semiconductor.
Lecture 15 - application of solid state materials solar cells and photovoltaics. Copying Nature... Anoxygenic photosynthesis in purple bacteria Simple example, but still complicated... Photosynthesis is
Evaluation of combined EBIC/FIB methods for solar cell characterization Frank Altmann*, Jan Schischka*, Vinh Van Ngo**, Laurens F. Tz. Kwakman**, Ralf Lehmann** *Fraunhofer Insitute for Mechanics of Materials
Background Photoelectrochemical solar cells are devices consisting of a photoelectrode, a redox electrolyte, and a counter electrode. i Semiconducting materials such as single-crystal and polycrystal n-
Solid State Devices Dr. S. Karmalkar Department of Electronics and Communication Engineering Indian Institute of Technology, Madras Lecture - 11 Equilibrium Carrier Concentration (Contd.) This is the 11th
Crystal Growth How do single crystals differ from polycrystalline samples? Single crystal specimens maintain translational symmetry over macroscopic distances (crystal dimensions are typically 0.1 mm 10
Properties of optical thin films produced by reactive low voltage ion plating (RLVIP) Antje Hallbauer Thin Film Technology Institute of Ion Physics & Applied Physics University of Innsbruck Investigations
University of Massachusetts - Amherst ScholarWorks@UMass Amherst Clean Energy Connections 11-22-2008 Fueling the Future through Chemical Energy of Fuel Cells, Solar Cells, and More DV Venkataraman University
April. 15, 2010 Due April. 29, 2010 Project 2B Building a Solar Cell (2): Solar Cell Performance Objective: In this project we are going to experimentally measure the I-V characteristics, energy conversion
Digital VLSI design Lecture 2: Complementary Metal Oxide Semiconductor (CMOS) Chips What will we learn? How integrated circuits work How to design chips with millions of transistors Ways of managing the
LED Review Questions 1. Consider two samples in the form of powders: sample A is a physical mixture comprising equal moles of pure Ge and pure Si; sample B is a solid solution of composition Si0.5Ge0.5.
How to Achieve the Sunshot Goal of $0.50/watt at the Module Level Using Compound Semiconductors? Industrial Perspective Materials Research Society Symposium D, Spring 2011 San Francisco, CA Robert G. Wendt
1 Metallization ( Part 2 ) Chapter 12 : Semiconductor Manufacturing Technology by M. Quirk & J. Serda Saroj Kumar Patra TFE4180 Semiconductor Manufacturing Technology, Norwegian University of Science and
1.5 Light absorption by solids Bloch-Brilloin model L e + + + + + allowed energy bands band gaps p x In a unidimensional approximation, electrons in a solid experience a periodic potential due to the positively
Impact of Materials Prices on Cost of PV Manufacture Part I (Crystalline Silicon) Nigel Mason SMEET II Workshop, London 27 Feb 2013 content Brief introduction to Solar PV Technologies Part I - Crystalline
DIRECTORATE FOR QUALITY AND STANDARDS IN EDUCATION Department of Curriculum Management Educational Assessment Unit Track 3 Annual Examinations for Secondary Schools 2015 FORM 3 CHEMISTRY TIME: 1h 30min
SunPower Cell and Module Technology: Overview and Advantages Oliver Koehler May, 2009 SunPower - A Differentiated Technology Highest Efficiency Cells and Modules Best Energy Performance (kwh/kwp) Solid
9 Solar Cell Parameters and Equivalent Circuit 9.1 External solar cell parameters The main parameters that are used to characterise the performance of solar cells are the peak power P max, the short-circuit
vistaris histaris Inline Sputtering Systems Inline Sputtering Systems with Vertical Substrate Transport Modular System for Different Applications VISTARIS Sputtering Systems The system with the brand name
Optical Hyperdoping: Transforming Semiconductor Band Structure for Solar Energy Harvesting 3G Solar Technologies Multidisciplinary Workshop MRS Spring Meeting San Francisco, CA, 5 April 2010 Michael P.