ontents semicon.kuee.kyoto-u.ac.jp P 5.47 ev 1.12 ev Ge 0.66 ev Sn 0.08 ev DVD LSI, 3.20 ev GaN 3.42 ev ZnO
2004/4/16 (Power Technology) O 2 ( ) (Information Technology) ( ) Gas (4H) GaN andgap (ev) 1.12 1.43 3.26 3.39 Electron mobility (cm 2 /Vs) 1350 8000 1000 1000 reakdown field (MV/cm) 0.3 0.4 3.0 3.0 Saturation velocity (cm/s) 1x10 7 1x10 7 2x10 7 2x10 7 Thermal conductivity (W/cmK) 1.5 0.5 4.9 1.3 (V/cm) (,Gas) (cm/s / V/cm) (cm/s) V 0 Schottky ontact n - n + Ohmic ontact ~ (V/cm) (cm) 2 ( cm) (cm) (cm 2 ) Field Electric n n + E c () E c () locking Voltage; V = (E W D )/2 arrier oncentration; N D = ( / q)(e / W D ) = E 2 / 2qV On-state Resistance; R on = W D / q n N D = 4 V 2 / n E 3 On-state Resistance R on, = R on, / 400 @same blocking voltage Drift Layer Thickness S PEIFI ON-RESISTNE ( c m 2 ) 10 0 10-1 10-2 10-3 4H- 10-4 10 2 10 3 10 4 REKDOWN VOLTGE (V) : 500V (GaN ) On-state Resistance R on = W / q N = 4 V 2 / E c 3 apacity (V) 1 0 9 1 0 8 1 0 7 1 0 6 1 0 5 1 0 4 1 0 3 THY. D Transmission GTO PT Telephone Line POWER-I Large Factory IGT ullet Train MOSFET UPS Inverter Electric Vehicle Switching Power Module 1 0 1 1 0 2 1 0 3 1 0 4 1 0 5 1 0 6 1 0 7 Operating Frequency (Hz) 2
Gas,GaN Source Gate Drain Source Gate ( ) Drain Lg GaN 2 vsat ( 30GHz 1cm) f T Lg V E L g RF Power (W) 1000 100 10 1 0.1 roadcast Microwave Oven ellular ase Station Trunk Radio Digital ellular nalog ellular Digital ordless III-N WLL WLN ITS ET Phased rray Radar VST S S LMDS P-MP WLN Gas Satellite ommun. P-P ar Radar 1 10 100 Frequency (GHz) / / / MOS Epitaxial Growth (VD) 30 hemical Vapor Deposition Ge Source gases: H 4, 3 H 8, H 2 Temperature: 1500~1550 o Gas Growth rate: 3~5 µm/h Substrates: 8 o off-axis 4H-(0001), (0001) 10 4H-(1120) prepared by slicing ( ree ) ) [0001]-grown ingots 4H-(0338) old-wall VD Hot-wall VD
(0001) oncept of of Step-controlled Epitaxy 4H- (0001) 4H- 4H- on-axis (0001) 3- DPT 6H- 4H- 4H- 4H- 3- (DPT) off-axis (0001) 6H- 3-6H- 6H- 6H- unique occupation-site at a step 2D nucleation polytype mixing Step-flow growth polytype replication 2 possible sites on a {0001} terrace 1750V Schottky Diode. Itoh, T. Kimoto and H. Matsunami, Int. Symp. on Power Semiconductor Devices and I s Yokohama, 1995 V vs vs R on on - Schottky Diodes SPEIFI ON-RESISTNE (Ωcm 2 ) 10 0 10-1 10-2 10-3 emens NSU Purdue emens Kyoto NSU Motorola Kyoto Purdue Linkoping Linkoping 4H- 10-4 10 2 10 3 10 4 REKDOWN VOLTGE (V) On-state Resistance R on = W / qµn = 4 V 2 /εµe c 3 III (III-N) () III-N/ / / / MOS III-N/
(0001) ln MOSFET O 2 / MOS III-N ln (ln/ ) ln/ MISFET MESFET GHz : / ~0.9% n-gan : 2H / 4H (or 6H) GaN/ HT : III-V / IV-IV ( ) MISFET,HT: Polytypes of of rystal 3-4H- 6H- a = 0.31 nm c / n = 0.25 nm atom atom Unit cell 15R- Growth method Plasma-assisted ME Elemental l and Ga ctive nitrogen (N*) EPI Unibulb rf-plasma cell Substrate Temperature 600~1000º (T..) Substrate commercially available 4H- (0001) 6H- (0001) off-angle: 0.1~0.3º 2H-lN 6H- unit cell 6H- unit cell 2H-lN 6H- 1 (6ML) Hl/H2 1300 o 6ML 6H- 2H-lN (SM) 6ML unit cell 6H- unit cell 6H- 2H x 3unit = 6ML 2H-lN 6ML -
ln/ ln/ 3 in-situ RHEED in-situ XPS l N -N = 1 N 3. Ga -N = -l ( ) 1000º 1. Hl 2. HF RHEED XPS (a) as-etched (b) HF-treated (c) HF/Ga-treated ( 3 3) R30 (1 1) ( 3 3) R30 /: -rich Oxygen (-O) lica adlayer O /: -rich Oxygen (no chemical shift) /: -rich Oxygen-free 1/3ML adlayer 2 0 100 200 300 60 as-etched 50 (ordered silicate adlayer) 40 30 50 40 30 20 30 20 HF-treated (oxgen-adsorbed (1x1)) HF/Ga-treated (oxgen-free 1/3ML adlayer) 0 2 4 6 8 Oxgen-free 1/3ML adlayer is suitable for initial 2D growth RHEED Growth Mode vs Growth Temperature 1. (3D ) 2. or ln Growth time (sec) 1ML - 2D 60nm-thick ln 0 100 200 300 200 nm 2 RHEED intensity RHEED intensity 1000 o growth 800 o growth 600 o growth 0 100 200 300 ln growth time (s) III/V 600 o 800 o,1000 o (Gas)
Surface Morphology for Various Thickness Tsub=800 o, on 4H- 8 ML 16 ML 32 ML Model for Growth Evolution 2H-lN 4H- 2D nucleation = 4ML 1ML 2D 2D 2D, Step-flow XR FWHM (arcsec) 800 600 400 200 0 3000 2000 1000 (0002) 60 @ 100 nm (0114) 450 @ 100nm 180 @ 100 nm as-etched (3D growth) HF/Ga-treated (2D-growth) 1000 o 600 o as-etched (3D growth) 1000 o 600 o 0 10 0 10 1 10 2 10 3 ln layer thickness (nm) 2 [ 10-8 ] 5 (0002), (0114) 4 3 1000 o 600 o 2 (0114) 1 2 0 5 10 15 Drain voltage (V) 1000 o 2D Drain current () ln ~ III-N with non-polar growth direction ln/ Spontaneous & piezoelectric polarization along c-axis ( ) c-axis Good: High density 2DEG in HEMT ln ad: Spatial separation e-h in QW (1120) (1120) resulting in low emission efficiency (0001) ( 3 3 )R30 2H-lN 6H- 6H-lN 6H- Utilizing non-polar growth direction such as [11-20] or [1-100] High quality grown layer is a key hoice of substrate and crystal plane c-axis
RHEED HRTEM for ln/4h- ~ 4H-lN!! 0000 2110 1010 0110 1210 1120 0000 2110 1210 1120 Model for interface at faulted region HRTEM on ln/6h- ~ 2H-lN interface XR (1120) diffraction High Quality -1000 0 1000 ω (arcsec) -1000 0 1000 ω (arcsec) -2000 2000-2000 2000 Gas -2000-1000 0 1000 2000-2000 -1000 0 1000 2000 ω (arcsec) ω (arcsec) nisotropy nature of crystalline quality due to symmetry of the surface. Intensity (arb. unit) Intensity (arb. unit) Intensity (arb. unit) Intensity (arb. unit) 21 IT,PT
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