SiC activities at Linköping University

Transcription

1 SiC activities at Linköping University A. Henry and E. Janzén

2 SiC : Prof. Erik Janzen growth (bulk and epi) defect and characterisation Nitride : Prof. Bo Monemar growth optical characterisation Electronic Structure : Prof. L. Johansson photoemission Spintronic : Prof. Weimin Chen Magneto-optic measurements Compound Semiconductors : Prof. Per-Olof Holtz optical characterisation

3 SiC activities Growth Bulk Sublimation High temperature CVD Epitaxy Horizontal Hot Wall CVD Vertical Hot Wall CVD Sublimation Epitaxy LPE Simulation Characterization Optical PL, PLE, Time resolved PL, FTIR, FTPL, CL Electrical Hall, IV, CV, DLTS, MCTS Magnetic resonance ODMR, EPR Structural XRD, Lang topograph Theoretical calculation S-Science : Sensor application Thin Film : TEM

4 High-Power diode SiC diodes Contacts p n Junction Termination Passivation Si IGBTs N + Substrate Active layer 2.5kV : 30 µm thick CVD n - 1.5E15 cm -3

5 Horizontal Hot-Wall CVD epilayer Quartz tube Insulation Graphite Substrate Coil Gas Inlet H 2 carrier SiH 4 + C 3 H 8 Doping (N 2, TMA ) Growth Temperature: 1600 o C in horizontal Growth Pressure: mbar O. Kordina C. Hallin : surf. prep., precursor U. Forsberg :MESFET Ö. Danielsson :Simulation

6 Simulation Ö. Danielsson Temperature Doping concentration (cm -3 ) Si-face C-face N Doping C/Si ratio Inlet C 3 H 8 flow (ml/min) Growth Rate Growth rate (µm/h) Doping concentration (cm -3 ) mbar 13 l/min Position along gas flow direction (mm) Inlet C 3 H 8 flow (ml/min) Si-face C-face Inlet SiH 4 flow (ml/min)

7 Degradation : Drift of the forward current 200 Virgin device Intermediate Stressed Creation and expansion of stacking faults Cathodoluminescence CL X-ray Topography 150 Ja[A/cm2] ,5 3 3,5 4 4,5 Va[V] P. Bergman

8 P. Bergman Lang topo [1,-1,] PL at 77K Cathodoluminescence CL X-ray Topography 6 x 4 5 Low Temperature PL Normal Spectra New Defect Emission PL Intensity Photon Wavelength (nm)

9 Today (2 inch diam) Thickness typically µm (80 µm) Unif = σ/mean < 8% Background doping level n-type (nitrogen) 1-2E14 N-doping 1E15 5E18 Unif < 20% Al-doping 5E15 1E19 Unif <20% Typical lifetime (35 um, 2E15) > 250 µs Future work related to SiC-CVD - Degradation : reduction of critical defects - Lifetime limiting defects - growth on non-standard surface - δ-doped layers - Regrowth - Other dopant : P, As, B, V

10 High Temperature CVD Bulk Seeded Sublimation Growth O. Kordina A. Ellison Insulation 1 Seed Crystal RF Coil RF Coil Source T process: C Seed Heater Crucible Quartz tube Graphite Foam HTCVD advantages: high vacuum high purity of the sources gases continuous supply of the source material possibility to adjust C/Si Gas Inlet Helium carrier SiH + C H 4 2 4

11 Id (ma) High Frequency Device SiC MESFET with Commercial S.I. substrate Degradation of I-V static characteristics Vgs=0V, -2V/step I DS (ma) V GS = 0 V SiC MESFET with PURER SUBSTRATE (HTCVD) (80 V STRESS) I DS (V DS ) Light ON Light OFF MESFET 1 0 µm V GS = -2 V/step Vds (V) V DS (V) C. Brilinski ECSCRM JESICA PROJECT

12 2-inch diameter 4H-SiC substrates pilot products SI on- and off-axis P+ N+ off-axis off-axis

13 Future work related to HTCVD Characterization : - identification of defects in SI SiC and understand their properties - Support to Okmetic (SI, N and P substrates)

14 Characterization Most studied defects in SiC after irradiation / implantation and annealing (2 MeV T>1200 C) Optical Electrical D 1 : Speudo-donor Z 1,2 PL intensity (arb.units) PL L 1 1S (T. Egilsson) PLE M 1 1 E C L 1 62 mev Photon Energy (mev) 2S 3S4S S-like P-like 0 P -like +/ - series limit 4H-SiC C/C (arb. units) HS1 E V ev MCTS (hole trap) DLTS (e lectron trap ) Z ½ E C ev 4H -SiC Temperatu re (K) (L. Storasta)

15 - Association D1 HS1-3 Z 1/2 (cm ) -3 HS1 (cm ) PL L /Q Annealing temperature ( C) (L. Storasta) - 3 DLTS & MCTS concentrat ion (cm ) 4H Si C PL L /Q s, 2p 1s L ev CB 2.9 ev VB 62 mev HS1

16 Characterization Defect study : Atom displacement C : 90 kev Si: 220 kev Face dependent? N-type 2.5E15 cm -3 epi Low energy electron irradiation kev L. Storatas DLTS/MCTS signal (arb.units) Electron traps Hole traps HS2 EH1 Z 1/2 EH3 DLTS MCTS EH Temperature (K)

17 Si-face 4H epilayer Introduction rate (arb.units) HS2 EH1 EH6 EH3 Z 1/2 C/Si face concentration ratio 1 EH1, EH3, Z 1/2 HS Irradiation energy (kev) Irradiation energy (kev) L. Storatas C related centers

18 Photoluminescence F. Carlsson PL Intensity (a.u.) log(plintensity) (a.u.) 5 4 L 1 L 1 g 2 g 2 g 1 g 1 f1 e1 e kev 160 kev TEM electrons 120keV c 2 d 1 c 1 d 1 c 2 c 1 b1 b 1 Si-Side Si-side a 1 C-Side C-side Wavelength ( Å) Wavelength (Å) a 1 PL Intensity (a.u.) PL Intensity (a.u.) L 1 L 1 g 2 g 1 g 2 g 1 e2 e 1 e 1 c 2 d 1 c 1 c 1 d1 c 2 PCB990 min TEM irradiation 160keV b 1 b 1 a 1 a 1 d 1 phonon band c 1 phonon band Si-Side b 1 phonon band b 1 (78meV) b 1 phonon band b 1 (78meV) Wavelength (Å) Wavelength (Å) 4H-SiC T=2K Si-side C-side C-Side