Materials Engineering at the ZMNS: From Nanostructures to Optoelectronic Devices

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1 Materials Engineering at the ZMNS: From Nanostructures to Optoelectronic Devices Gottfried Strasser Institut für Festkörperelektronik Zentrum für Mikro- und Nanostrukturen Fakultät für Elektrotechnik und Informationstechnik Technische Universität Wien October IV EU-RUSSIAN OPEN DAYS

2 Center for Micro- and Nanostructures October IV EU-RUSSIAN OPEN DAYS

3 Cleanroom area 500m 2 (class 100 and 10000) Solid State Electronics Microelectronics Photonics Sensor and Actuator Systems Microwave and Circuit Engineering Physics Materials Engineering

4 ZMNS EE Institut für Festkörperelektronik (solid state electronics) Institut für Mikroelektronik (microelectronics) Institut für Photonik (photonics) Institut für Sensor- & Aktuatorsysteme (sensor and actuators) Institut für elekt. Mess- & Schaltungstechnik (circuit design) TU Vienna Atominstitut (atomic institute) Institut für Allgemeine Physik (general physics) Institut für Festkörperphysik (solid state physics) Institut für Anorganische Chemie (inorganic chemistry) External User

5 Molecular Beam Epitaxy Veeco (Intevac) mod GenII : Ga, Al, In, As // Si, C Riber P32: Ga, Al, In, N, Sb, As //Si XRD (Philips Expert)

6 Lithography - Contact lithography (2x SUSS MJB3, 1 EVG) - Mask production (GCA 3600)

7 EBL Electron Beam Lithography Laser interferometer stage 100 mm by 100 mm travel range 2 nm resolution piezo-positioning Minimum line width < 20 nm Stitching accuracy 40 nm Overlay accuracy 40 nm 18.2 nm

8 Plasma Systems: Etching & Coating Plasma-enhanced CVD processing dielectrics Reactive Ion Etching

9 RIE ICP Etching of Si & GaAs/AlGaAs/InGaAs & GaN trench 8µm, ridge 20µm, depth 40µm GaAs ICP etching Silicon ICP etching etch rates : 1µm/min trench 8µm, ridge 4µm, depth 40µm

10 Thin Film Technology Evaporators thermal e-beam Sputter RF-magnetron DC low rate

11 Coating and Bonding - Spray coating - Wafer bonding - Double sided aligning

12 Analysis - Focused Ion Beam - Electron Beam Microscope - AFM - Dektak - Ellipsometry

13 Research Topics: Project Name Funding Project Name CoQuS Euro Graphene HipoSwitch HiTGaN ICARUS Ionenstrahlinduzierte Nanodrahtsynthese IRON II: III-V based IR nanodevices IRON II: IR response of nanostructures IRON II: Electronic transport in nanostructures PLATON THz Photonics PLATON III-V Nanostructures Plasmonic IR Devices RTN: Novel Materials Funding FWF FWF EU-ICT EU-ICT EU-IP FWF FWF SFB FWF SFB FWF SFB FFG FFG EC EU Microdisc Laser WWTF Microstructured Bioelectronic Interfaces Monolithische Integration FWF von Nanodrähten MORGAN EU-NME Nanonoise FWF NILdirect_stamp FFG NSI - NanoScapel FFG Scanning FWF Electroluminescence Microscopy on Nanostructures Spectrosmart FFG plus projects funded by companies

14 High-k Materials high-k nano wire transistors Y 2 O 3 and ZrO 2 MOS-Structures vertically integrated nanowire field effect transistor Single crystalline Si-NW AG E. Bertagnolli

15 Advanced Lithography Imprint Lithography large area fabrication of nanopatterned surfaces Maskless Lithography direct-writing with focused e-beams AG E. Bertagnolli

16 Integrated Sensor Systems Physical chemosensors, biochips, microfluidics, MEMS sensors 3D fluidic lens Lorentz-force viscosity sensor Technology: Silicon MEMS, glass, ceramics, SU-8, microstereolitho, 2-photon structuring 2-photon lens AG M. Vellekoop

17 from nanostructures C C E E B B to optoelectronic devices

18 Motivation intersubband transitions Electronics Terahertzgap Photonics 10 9 Hz Hz Hz Hz Hz Hz Hz Hz Frequency Radiowellen MM MW FIR MIR NIR VIS UV X-Rays 30 cm 3 cm 3 mm 300 µm 30 µm 3 µm 300 nm 30 nm Wavelength intraband laser Applications µm Fingerprint region Continuous pollutant analysis, trace monitoring optical communication (wireless LAN) in the atmospheric windows medicine applications / scanners (security) / counter measures Basic science new material combinations & concepts telecom wavelength sources & detectors room temperature THz sources

19 Semiconductor heterostructures conduction band quantum well AlGaAs GaAs AlGaAs energy growth direction growth direction valence band 2D electron gases, phemts (FETs), tunneling diodes (RTDs), quantum wells (MQWs), superlattices (SLs), hot electron transistors, light emitting diodes (LEDs), semiconductor laser, QW laser, VCSELs, QCLs, THz laser, detectors (QWIPs), Bragg reflectors,

20 Optoelectronic devices interband laser QW Laser intraband laser QC Laser ћω E gap = 1.5 ev ћω = ev CB VB

21 Quantum Cascade Laser (QCL) e injector injector active region radiative transition An electron streams down a staircase and emits a photon at each step. Cascade: one electron can emit as many photons as cascades.

22 Device Fabrication for QCLs Design growth of nanostructures waveguide design distance (µm) spacer active spacer substrate mode intensity n+ n+ Fabry-Perot DFB micro-cavity

23 Nanostructured Devices processing DFB Coupled Cavity Bragg mirror Y-coupled QCL Surface emitter MIR Disks & Rings Lateral & Ring DFBs THz Disks & Rings PBG QCs

24 Design & Fabrication Mix & Match processing radial grating with e-beam lithography 200 µm ridges, insulations, contacts with standard UV-lithography 40 µm Extended contact Insulation Au-grating 10 µm

25 MIR Ring-CSEL vs. FP ring-csel FP narrow circular beam (~1.5 ) ring shaped pattern (interference pattern) high beam divergence ~30 (10µm ridge)

26 Spectra Signal (norm.) Wavelength (µm) a) FP ring-csel Λ= µm 100 khz/20 ns 78 K 10 ka/cm Wavenumbers (cm -1 ) Signal (norm.) Wavelength (µm) b) FP ring-csel Λ= µm 100 khz/20 ns 293 K 6 ka/cm Wavenumbers (cm -1 ) Signal (norm.) Frequency (THz) Wavelength (µm) c) FP ring-csel Λ= µm 50 khz/1 µs 10 K 1.8 ka/cm Wavenumbers (cm -1 ) λ~4 µm λ~8 µm λ~93 µm (3.24 THz) side mode suppression ratio (SMSR) higher than 25 db Signal (norm.) Wavelength (µm) a) Λ= µm 100 khz/20 ns 78 K 10 ka/cm Wavenumbers (cm -1 ) Signal (norm.) Frequency (THz) Wavelength (µm) c) Λ= µm 50 khz/1 µs 10 K 1.8 ka/cm Wavenumbers (cm -1 )

27 Broadband Array Widely spectral tunable array λ 1 λ 2 16-ring-CSEL broadband array 1mm λ n-1 λ n + =

28 Spectra linear spectral tuning tuning range ~180 cm -1 SMSR ~25 db

29 Spectral Dependency threshold current density is not influenced by the cavity (grating design, since no facets are present) power and threshold variations given by gain profile ITQW 2011, Sardinia

30 Outlook coherent coupling coherent high power array λ 1 widely spectral tunable array λ 1 λ 2 2D beam steering λ n-1 λ n

31 Thanks to and thank you for your attention!

32 GaN High Power Transistors InAlN/GaN barrier recessing GaN passivation eliminates the gate lag effect Fabrication and analysis of normally-off InAlN HEMTs MOS GaN transistors with different dielectric layers