スライド 1

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ひでかやまのかみしゃ
5 years ago
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1 Matsuura Laboratory SiC SiC

2 H-SiC ( C-SiC HOY

3 Matsuura Laboratory

4 n E C E D ( E F E T Matsuura Laboratory

5 Matsuura Laboratory DLTS

6 Osaka Electro-Communication University Unoped n 3C-SiC Electron concentration (cm -3 ) /T (K -1 ) Matsuura Laboratory

7 Osaka Electro-Communication University Matsuura Laboratory ln n ( T ) 1/ T Hoffmann H ( T, E ref ) n( T ) ( kt ) 2 5 / 2 exp E ref kt

8 Osaka Electro-Communication University ln n ( T ) 1/ T 1 E D =124 mev N D =1x10 16 cm -3 ) N D =1x10 16 cm -3 n ( T ) [ c m - 3 ] E D =127 mev E n( T ) exp D 2kT / T [ K - 1 ] Matsuura Laboratory

9 E D1 =124 mev N D1 =1x10 16 cm -3. ( E D2 =64 mev N D2 =5x10 15 cm -3 ) B. (N =1x10 15 cm -3 ) n(t) [cm -3 ] E D =54 mev N D =1.48x10 16 cm -3 E D =251 mev N D =8.9x10 15 cm /T [K -1 ] B

10 Osaka Electro-Communication University n( T ) n = N C ( T ) exp E kt F n ( T ) = ND i[ 1 fd( EDi )] N i= 1 n N Di E Di N (2n+1) Matsuura Laboratory

11 Matsuura Laboratory Osaka Electro-Communication University Electron concentration (cm -3 ) n 3C-SiC /T (K -1 )

12 Osaka Electro-Communication University kt dn( T ) de F Hoffmann EF?? Spline

13 Osaka Electro-Communication University Free Carrier Concentration Spectroscopy (FCCS) n(t) H ( T, E ) ref T peaki n ( T ) ( kt ) E Di E k peak i, Eref ) 2 5 / H1( T ref 2 N kt exp Di peaki E ref kt Matsuura Laboratory

14 Matsuura Laboratory FCCS Windows

15 Osaka Electro-Communication University Undoped 3C-SiC (100) n Si Si 2 (CH 3 ) C-SiC 32 m Si 5x5 mm 2 5 kg 1 m 85 K~500 K Matsuura Laboratory

16 Matsuura Laboratory Osaka Electro-Communication University Spline

17 Matsuura Laboratory Osaka Electro-Communication University FCCS H ( T, Eref ) n( T ) ( kt ) 2 5 / 2 exp E ref kt 51 mev 7.1x10 16 cm -3

18 Theoretical expression of FCCS signal is H ( T, E ref ) = i N N kt C0 kt Di N exp E exp E ref Di kt E kt E ref F I D ( E ) Di FCCS signal, in which the influence of the previously determined donor species ( E D2, N D2 ) is removed, is 2 n( T ) E N E E H 2 ref E 5 / 2 D ( kt) kt kt kt ref D2 D2 ref ( T, E ) = exp exp I ( ) D2

19 H2 Osaka Electro-Communication University 2 n( T ) E N E E H 2 ref E 5 / 2 ( kt) kt kt kt ref D2 D2 ref ( T, E ) exp exp I( ) D mev 3.8x10 16 cm -3 Matsuura Laboratory

20 H3 Osaka Electro-Communication University Matsuura Laboratory 114 mev 1.1x10 17 cm -3

21 Osaka Electro-Communication University

22 Matsuura Laboratory Osaka Electro-Communication University Undoped 3C-SiC FCCS 3 18 mev 51 mev 114 mev? FCCS H.Matsuura et al. Jpn. J. ppl. Phys. 39(2000)5069.

23 .Matsuura et al. J. ppl. Phys. 96(2004)7346. Donor Level [mev] n 3C-SiC Total Donor Density [cm -3 ] E E E D3 D2 D = = N D N N D D

24 Osaka Electro-Communication University n 4H-SiC H.Matsuura et al. J. ppl. Phys. 96(2004) n-type 4H-SiC epilayer N D [cm -3 ] Donor Level [mev] E 5 D2 = N 3 D Simulation using E D1 (N D ) = x10-5 1/3 N D E D2 (N D ) = x10-5 1/3 N D Doping Donor Density [cm -3 ] E 5 D1 = N 3 D

25 Problem in heavily doped p-type wide bandgap semiconductors The acceptor density, which is determined by the curve-fitting method using the temperature dependence of the hole concentration, is always much higher than the doping density.

26 Hole Concentration [cm -3 ] Heavily l-doped 6H-SiC Heavily l-doped 6H-SiC : Experimental p(t) /T [K -1 ] 2. C-V characteristics f 1. Hall-effect measurement Fermi-Dirac (FD) distribution function FD N ( E ) N = = 1 = E 1+ 4exp mev E kt Results determined by curve-fitting E = 180 cm cm FD F 3 3

27 E r 1 m 1 = 13.6 h ε m r 2 2 s * 0 [ev] p-type wide bandgap semiconductors (GaN, SiC, diamond) 1. Si 2. Semiconductor cceptor level (r=1) 1 st excited state level (r=2) SiC 146 mev 37 mev GaN 101 mev 25 mev Si B (45 mev)

28 E F (T) [mev] Position of Fermi level in 6H-SiC : Heavily l-doped 6H-SiC : Lightly l-doped 6H-SiC E cceptor levels E F (T) E E F (T) E V Temperature [K] Heavily doped case 1 st 2 nd

29 1. f FD ( E ) = 1+ g exp 2. f ( E ) = 1+ g ( T )exp 1 E E kt kt E E 2 g g (T) 1 F F

30 cceptor degeneracy factor In f FD ( E ) g = 4 In f ( E ) g E E E T T = g + g r ( ) ( ) 1 r exp exp ex r= kt kt 2 Degeneracy factors of excited states Excited state levels verage energy of acceptor level and excited state levels E ( ) Er E Er g r exp r= 2 = kt E ex ( T ) E + Er 1 g r exp r= 2 kt H. Matsuura New J. Phys. 4(2002)12.1.

31 Heavily l-doped 6H-SiC Hole Concentration [cm -3 ] Heavily l-doped 6H-SiC : Experimental p(t) /T [K -1 ] H ( T, E ) H(T,0.248) [x10 42 cm -6 ev -2.5 ] p( T ) ( kt ) exp Heavily l-doped 6H-SiC Peak Temperature [K] From the peak, N = cm -3 and E =180 mev for f FD ( E ) N = cm -3 and E =180 mev for f ( E ) Since the l-doping density is cm -3, the influence of excited states on p(t) should be considered. ref 2 5/ 2 E kt ref

32 FCCS H(T,0.248) [x10 42 cm -6 ev -2.5 ] Heavily l-doped 6H-SiC Experimental H(T,E ref ) Simulated H(T,E ref ) : f FD ( E ) : f( E ) H ( T, E ref ) = N N 1 kt V0 E exp kt N D 1 E exp kt ref E E kt ref I F ( E ) Temperature [K] The H(T,E ref ) simulation for f( E ) is in better agreement with the experimental H(T,E ref ) than that for f FD ( E ).

33 Heavily doped 6H-SiC Lightly doped 6H-SiC f( E ) f FD ( E ) f( E ) f FD ( E ) N [cm -3 ] 3.2x x x x10 15 E [mev] Doping density [cm -3 ] 4.2x10 18 ~6x10 15 Only in heavily doped samples, f FD ( E ) cannot be used to analyze p(t). H. Matsuura J. ppl. Phys. 95(2004)4213.

34 Matsuura Laboratory

35 cceptor degeneracy factor In f FD ( E ) g = 4 + = = kt T E kt E E g g T g r r r ) ( exp exp 1 ) ( ex 2 Degeneracy factors of excited states In f ( E ) ( ) = = + = 2 2 ex exp 1 exp ) ( r r r r r r r kt E E g kt E E g E E T E verage energy of acceptor level and excited state levels Excited state levels

36 f ( E ) = 1+ g ( T 1 )exp E kt E F 4 p-type 6H-SiC 3 g (T) 2 1 Simulations : g (T) : g Temperature [K] g (T) 4

37 Ionized cceptor Density [cm -3 ] Heavily l-doped 6H-SiC Simulations N = 3.2x10 18 cm -3 E = 180 mev N D = 9.0x10 16 cm -3 : f FD ( E ) : f( E ) Temperature [K]

38 Ionized cceptor Density [cm -3 ] Lightly l-doped 6H-SiC Lightly l-doped 6H-SiC N - (T) simulations N = 4.1x10 15 cm -3 E = 212 mev N D = 1.0x10 14 cm -3 : f FD ( E ) : f( E ) Temperature [K] Lightly doped

39 Osaka Electro-Communication University cceptor Level [mev] p 4H-SiC l l-doped 4H-SiC epilayers cceptor Density [cm -3 ]. Matsuura et al. J. ppl. Phys. 96(2004)2708.

40 Matsuura Laboratory

41 2 MOS d Ψ q = D 2 dx ε Poisson equation ( + ) N N + p n S ε 0 SiO 2 n + p p n + n - n + resistivity ρ = 1 qµ n n 1 σ = Matsuura Laboratory

42 Matsuura Laboratory

43 Osaka Electro-Communication University Electron Mobility [cm 2 V -1 s -1 ] n-type 4H-SiC Epilayers Doping density [cm -3 ] : 8.8x10 14 : 2.2x10 15 : 2.4x10 15 : 3.5x10 16 : 6.8x10 16 : 9.4x Temperature [K] β( N T D ) µ n( T, ND ) = µ n( 300, ND ) 300

44 Osaka Electro-Communication University β β(n D ) ( N ) D = N D : Experimental : Simuration n-type 4H-SiC Doping Donor Density [cm -3 ] 17 S. Kagamihara et al. J. ppl. Phys. 96(2004)5601.

45 Osaka Electro-Communication University Electron Mobility [cm 2 /(V-s)] K Our results W.J.Schaffer et al H.Matsunami et al J.Pernot et al W.Gotz et al.schoner et al C.H.Carter Jr. et al S.Nakashima et al Simulation results Doping Donor Density [cm -3 ] S. Kagamihara et al. J. ppl. Phys. 96(2004)5601. µ n ( 300, N ) D = N D

46 H. Matsuura et al. J. ppl. Phys. 96(2004)2708. p 4H-SiC µ p ( T N ) = µ ( 300, N ), p T 300 β ( N ) β 0.53 ( N ) = N µ p ( 300, N ) = N

47 H. Matsuura et al. Jpn. J. ppl. Phys. 37(1998)6034. H. Matsuura et al. ppl. Phys. Lett. 79(2000)2092. H. Matsuura et al. Jpn. J. ppl. Phys. 42(2003)5187. p Si Divacancy Donor-like

48 Osaka Electro-Communication University p 4H-SiC 4.6 MeV H-SiC epilayer 2.6x10 14 cm -2 Hole Concentration [cm -3 ] : Before irradiation : fter irradiation / T [K -1 ] Before irradiation fter irradiation E 1 [mev] N 1 [cm -3 ] E 2 [mev] N 2 [cm -3 ] N D [cm -3 ] l H. Matsuura et al. ppl. Phys. Lett. 83(2003)4981.

49 Matsuura Laboratory FCCS

MOSFET HiSIM HiSIM2 1

MOSFET HiSIM HiSIM2 1 MOSFET 2007 11 19 HiSIM HiSIM2 1 p/n Junction Shockley - - on-quasi-static - - - Y- HiSIM2 2 Wilson E f E c E g E v Bandgap: E g Fermi Level: E f HiSIM2 3 a Si 1s 2s 2p 3s 3p HiSIM2 4 Fermi-Dirac Distribution