SiC activities at Linköping University

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

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

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

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

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: 50-00 mbar O. Kordina C. Hallin : surf. prep., precursor U. Forsberg :MESFET Ö. Danielsson :Simulation

Simulation Ö. Danielsson Temperature Doping concentration (cm -3 ) 18 17 Si-face C-face N Doping C/Si ratio 1.0 2.0 3.0 4.0 5.0 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Inlet C 3 H 8 flow (ml/min) Growth Rate Growth rate (µm/h) Doping concentration (cm -3 ) 6 5 4 3 2 1 00 mbar 13 l/min 1 2 3 4 0 0 20 40 60 80 0 Position along gas flow direction (mm) 20 19 18 Inlet C 3 H 8 flow (ml/min) 0.4 0.8 1.2 1.6 2.0 2.4 Si-face C-face 0.4 0.8 1.2 1.6 2.0 Inlet SiH 4 flow (ml/min)

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] 0 50 0 2 2,5 3 3,5 4 4,5 Va[V] P. Bergman

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 4 3 2 1 0 380 400 420 440 Photon Wavelength (nm)

Today (2 inch diam) Thickness typically 30-40 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

High Temperature CVD Bulk Seeded Sublimation Growth O. Kordina A. Ellison Insulation 1 Seed Crystal RF Coil RF Coil Source T process: 20 2300 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

Id (ma) 30 25 20 15 5 High Frequency Device SiC MESFET with Commercial S.I. substrate Degradation of I-V static characteristics Vgs=0V, -2V/step I DS (ma) 40 30 20 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 4522 0 0 20 30 40 Vds (V) 0 0 20 30 40 V DS (V) C. Brilinski ECSCRM 2000 + JESICA PROJECT

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

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

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 2900 2920 2940 2960 2980 Photon Energy (mev) 2S 3S4S S-like P-like 0 P -like +/ - series limit 4H-SiC C/C (arb. units) HS1 E V +0.35 ev MCTS (hole trap) DLTS (e lectron trap ) Z ½ E C -0.68 ev 4H -SiC 0 200 300 400 500 Temperatu re (K) (L. Storasta)

- Association D1 HS1-3 Z 1/2 (cm ) -3 HS1 (cm ) PL L /Q 1 0 0 500 00 1500 200 0 Annealing temperature ( C) (L. Storasta) - 3 DLTS & MCTS concentrat ion (cm ) 4H Si C PL L /Q 1 0 + 2s, 2p 1s L 1 0.35 ev CB 2.9 ev VB 62 mev HS1

Characterization Defect study : Atom displacement C : 90 kev Si: 220 kev Face dependent? N-type 2.5E15 cm -3 epi Low energy electron irradiation 80-300 kev L. Storatas DLTS/MCTS signal (arb.units) Electron traps Hole traps HS2 EH1 Z 1/2 EH3 DLTS MCTS EH6 160 240 320 540 660 Temperature (K)

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 HS2 150 200 250 300 Irradiation energy (kev) 0 120 140 160 180 200 220 Irradiation energy (kev) L. Storatas C related centers

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 1 120 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 4260 4280 4300 4320 4340 4360 4380 4400 4420 Wavelength ( Å) 4260 4340 4420 Wavelength (Å) a 1 PL Intensity (a.u.) PL Intensity (a.u.) 5 4 3 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) 4300 4350 4400 4450 4500 4550 Wavelength (Å) 4300 4440 4500 Wavelength (Å) 4H-SiC T=2K Si-side C-side C-Side