GaN AlGaN 欠陥準位 表面準位 - astf.or.jp

1 1 GaN. group Ho k k aid o U n iv e r s i t y GaN AlGaN .. 2 GaN. group Outline Ho k k aid o U n iv e r s i t y .. 1) AlGaN . 2) AlGaN . 3) p-GaN . 3 GaN. group AlGaN / gan hemt AlGaN PL/CL Ho k k aid o U n iv e r s i t y HEMT . Before stress After 150-h off-state stress . Meneghesso et al, ED, 2006 Onuma, Chichibu, JAP, 2004. 4 GaN. group GaN AlGaN Ho k k aid o U n iv e r s i t y GaN . Ec ~ eV .. Ga eV. Ev Mg . AlGaN . 5 GaN. group DLTS Ho k k aid o U n iv e r s i t y I-V C-V . 200 m Ti/Al/Ti/Au 102 5. Ni/Au n = 1/C2 (x 1014 F-2cm2). 100. B = 4. (A/cm2). 10-2. 10-4 3. -6. B = eV. 10. 2. 10-8. Si : 1x1017cm-3 1. -10. LT-GaN 10. sapphire 10-12 0. -4 -3 -2 -1 0 1 2 -4 -2 0 2 4. (V) (V). 6 GaN. group DLTS . Ho k k aid o U n iv e r s i t y DLTS . 106. DLTS signal T2 (K2 s). 105.

2 E= eV. t1/ t2 = 1/10 s s n= 5x 10-13 cm2. 10 . 104. 100 200 300 400 500 3. Temperature (K) 1000/ T (K-1). ~ 5x 1016 cm-3. 7 GaN. group Ho k k aid o U n iv e r s i t y 6 AlxGa1-xN. 10. Temperature-weighted time constant Park APL2005. ~ ~ Si-doped 0-15 MBE. 5. 10. ~ Hogsed APL2005. Si-doped 14 MBE. T2 (sK2). 104 ~ 1 MeV . 3 Osaka APL2005. 10 un-doped 9 17 HVPE. 2 . 10. Si-doped 26 MOVPE. 101. 0 2 4 6 8 10. 1000/T (K-1). 8 GaN. group 360 K . Ho k k aid o U n iv e r s i t y VR= 0V. illumination ( eV). hv Capacitance (pF). eV. deeper CPH level Optical emission of EFS electrons from a level dark ( < E < eV). eV. VR= -5V T= 360 K. 0. 0 200 400 7000 7500 8000 near-midgap Thermal emission of Time (s) levels electrons from the level 9 GaN. group AlxGa1-xN (x< ) Ho k k aid o U n iv e r s i t y EC.

3 EV. eV . (DLTS).. ~ eV midgap . ( . EV. 10 GaN. group HEMT CV Ho k k aid o U n iv e r s i t y 4 3. Capacitance (x 10-7 F/cm2). Capacitance (x 10-7 F/cm2). 0V sweep 3 300 K 0V -8V . f= 100 kHz 2. -8V . 2 . 1. 1. -8V . 10 . 0 0. -10 -8 -6 -4 -2 0 Voltage (V) Voltage (V). CV AlGaN . 5 x 1011 1 x 1012 cm-2. 2 4 x 1017 cm-3. 11 GaN. group Ho k k aid o U n iv e r s i t y Characterization of free AlGaN surface .. SPM PL .. 12 GaN. group AlGaN . Ho k k aid o U n iv e r s i t y Air-gap C-V characterization reflection bottom view prism upper laser plate beam air gap (200-500 nm). AlGaN . ground plate parallelism electrodes Position control stepping motor measurement electrode piezo actuator 13 GaN. group air-gap . Ho k k aid o U n iv e r s i t y 100. Normalized capacitance C/Cgap P-polarized light Si/SiO2 reference 80 1.)

4 Refrectivity(%). 60 laser exp air gap 40. ideal 20 laser: 780 nm 0. 0 200 400 600 800 1000 -20 -10 0 10 20 30. Air-gap length (nm) Voltage (V). The UHV gap was determined by measuring reflectivity that can be changed by penetration of evanescent wave. 14 GaN. group AlGaN ai-gap CV Ho k k aid o U n iv e r s i t y layer by MOCVD. high density ! EC. Surface state density (cm-2eV-1). 14. 10. Capacitance (pF) air gap: 320 nm upper electrode ideal 1013. air gap n- AlGaN . C 1012. n-GaN. measured 1011. midgap 1010. 1 m -100 -50 0 50 100 Gate voltage (V) Energy from EC (eV). 15 GaN. group Oxygen in AlGaN Ho k k aid o U n iv e r s i t y SIMS analysis p- AlGaN InAlGaN n- AlGaN n-GaN. High oxygen density 1017 ~ 1018 cm-3. in AlGaN . Kyono et al JAP, 2006. 16 GaN. group Effects of oxygen introduction to AlGaN surface Ho k k aid o U n iv e r s i t y Oxygen plasma 30 30.

5 N2O plasma virgin virgin 25 25. Drain Current (mA). 20 O2 plasma 20. S G D N2O plasma I (mA). 15 15. D. 10 10. GaN. 5 5. ECR, 50W. 0 0. 300 oC, 1min 0 2 4 6 8 10 0 2 4 6 8 10. V (V) V (V). DS. DS. Oxygen incorporation caused pronounced degradation of HEMT DC characteristics 17 GaN. group Possible origins of surface electronic states Ho k k aid o U n iv e r s i t y EC. VN .. density EV.. 1 x 1011 1 x 1013 cm-2eV-1. 18 GaN. group SiN passivation Ho k k aid o U n iv e r s i t y MOCVD EC. Surface control process 1014. Surface state density (cm-2eV-1). free surface n- AlGaN 1 m 1013. n-GaN. substrate 1012. SiN deposition by ECR-CVD SiN-passivated 11. 10. SiN midgap n- AlGaN . 300 oC 1010. n-GaN 20 nm substrate Energy from EC (eV). 19 GaN. group In-situ deposition of SiN Ho k k aid o U n iv e r s i t y 1000 oC.

6 SiH4 and NH3. mold Pronounced reduction of surface potential crystalline SiNX. (wurtzite-like) Increase in 2 DEG density Takizawa et al, JEM, 2008 Ogawa, Hashizume, JJAP 2007. 20 GaN. group SiN AlGaN Ho k k aid o U n iv e r s i t y Leakage current characteristics Small band offset at -1. 10. SiNx/ AlGaN interface 10-3 Ni/ AlGaN Ec= ~ eV. Current (A). 10-5 SiN/ AlGaN . -7. 10. eV. SiNx 10-9 eV. 10 -11. 10 -13. SiN/Si -5 0 5 Fowler-Nordheim (FN) leakage Voltage (V). points to note: leakage in MIS gate structure hot carrier injection in passivation structure Hashizume, JVSTB, 2003. 21 GaN. group Al2O3 Ho k k aid o U n iv e r s i t y EG. 10 400 . MgO. 3 Anneal 8 SiO2. Al2O3 450 . 6 AlN Anneal EG (eV). Si3N4 ZrO2 2. HfO2. 4. Ga2O3. GaN . 2 GaAs Si 1 . 0 . 0 5 10 15 20. dielectric constant, Al2O3.

7 26nm 0. Al2O3 AlGaN -10 -5 0 5. Voltage [V]. 22 GaN. group p-GaN Ho k k aid o U n iv e r s i t y GaN MOSFET . ? p-GaN . 23 GaN. group . Ho k k aid o U n iv e r s i t y XPS, SIMS. PL. 24 GaN. group Mg p-GaN XPS SiO2 . Ho k k aid o U n iv e r s i t y Ga3d Mg1s . 1100 . Intensity ( ). 1100oC. Intenisty( ). 1000 . 1000oC. reference Ga2s reference 24 22 20 18 16 14 1310 1300 1290. Binding Energy(eV) Binding energy(eV). 25 GaN. group Mg p-GaN XPS SiO2 Ho k k aid o U n iv e r s i t y Ga2p O1s . Intensity ( ). 1300 1200 1100 1000. Si 1500 1000 500 0. Binding energy(eV). 26 GaN. group Mg p-GaN PL . Ho k k aid o U n iv e r s i t y p-GaN:Mg . RT. Mg . Deep Ga . PL Intensity ( ).. 1 . o 1100 C. o VGa + MgI. 1 1000 C. VGa + O. as-grown 10. VN + MgI. Photon energy(eV). 27 GaN. group Summary Ho k k aid o U n iv e r s i t y 1) AlGaN AlGaN /GaN midgap.

8 2) Air-gap CV .. 3) AlGaN .. p-GaN Ga Mg.