SiC - Silicon Carbide

Silicon carbide crystallizes in numerous (more than 200 ) different modifications (polylypes). The most important are: cubic unit cell: 3C-SiC (cubic unit cell, zincblende); 2H-SiC; 4H-SiC; 6H-SiC (hexagonal unit cell, wurtzile ); 15R-SiC (rhombohedral unit cell). Other polylypes with rhornbohedral unit cell: 21R-SiC 24R-SiC, 27R-SiC etc.
In all polytypes except 3C- and 2H-Sif atomic layers with cubic (C) and hexagonal (H) symmetry follow in a regular alternation in the direction of the c axis. This can be thought of as a nutural one-dimensional superkmice imposed on the "pure" - i.e. h-layer free 3C-SiC [Dean et al.(1977)], the period of the superlaltice being different for different polylypes SiC.

Basic Parameters

Si-C Polytype 3C-SiC 4H-SiC 6H-SiC 15R-SiC
Crystal structure Zinc blende (cubic) Wurtzite ( Hexagonal) Wurtzite ( Hexagonal) Rhombohedral
Crystal structure T2d-F43m C46v-P63mc C46v-P63mc C53v-R3m
      Remarks Referens
Crystal structure 3C-SiC Zinc blende (cubic)  
  4H-SiC Wurtzite ( Hexagonal)  
  6H-SiC Wurtzite ( Hexagonal)  
  15R-SiC Rhombohedral  
Group of symmetry 3C-SiC T2d-F43m  
  4H-SiC C46v-P63mc  
  6H-SiC C46v-P63mc  
  15R-SiC C53v-R3m  
 
Bulk modulus  3C-SiC   2.5 x 1012 dyn cm-2 300 K Goldberg et al.(2001)
   4H-SiC 2.2 x 1012 dyn cm-2    
   6H-SiC 2.2 x 1012 dyn cm-2 theoretical estimation
0.97 x 1012 dyn cm-2 (experimental data)
 
Linear thermal expansion coefficient  3C-SiC 2.77 (42) x 10-6 K-1   Slack & Bartram (1975)
 
Debye temperature  3C-SiC   1200 K   Goldberg et al.(2001)
   4H-SiC 1300 K    
   6H-SiC 1200 K    
Melting point  3C-SiC   3103 (40) K p = 35 bar.
Peritectic decomposition temperature
Scace & Slack (1960)
   4H-SiC 3103 ± 40 K at 35 atm Tairov & Tsvetkov (1988)
   6H-SiC 3103 ± 40 K at 35 atm. see also Phase diagram Tairov & Tsvetkov (1988)
 
Density 3C-SiC 3.166 g cm-3 293 K Kern et al. (1969)
  3.21 g cm-3 300 K Harris et al.(1995b)
  4H-SiC 3.211 g cm-3 300 K Gomes de Mesquita (1967)
  6H-SiC 3.21 g cm-3 300 K Harris et al.(1995b)
 
Hardness 3C-SiC,
4H-SiC
6H-SiC
9.2-9.3 on the Mohs scale Goldberg et al.(2001)
 
Surface microhardness 3C-SiC,
4H-SiC
6H-SiC
2900-3100 kg mm-2 300 K,
using Knoop's pyramid test
Kern et al. (1969), Shaffer (1965)
 
Dielectric constant (static) 3C-SiC ε0 ~= 9.72 300 K Patric & Choyke (1970)
4H-SiC The value of 6H-SiC dielectric
constant is usually used
300 K  
Dielectric constant
(static, ordinary direction)
 6H-SiC ε0,ort ~= 9.66 300 K Patric & Choyke (1970)
Dielectric constant
(static, extraordinary direction)
6H-SiC ε0, || ~= 10.03 300 K Patric & Choyke (1970)
Ratio between the static dielectric constant
(ordinary and extraordinary direction)
6H-SiC ε0,ort / ε0, || ~= 0.9631 300 K  
Dielectric constant (high frequency) 3C-SiC 6.52 300 K Patric & Choyke (1970)
4H-SiC The value of 6H-SiC dielectric
constant is usually used
300 K  
Dielectric constant
(high frequency, ordinary direction)
6H-SiC εort ~= 6.52 300 K Patric & Choyke (1970)
Dielectric constant
(high frequency, extraordinary direction)
6H-SiC ε || ~= 6.70 300 K Patric & Choyke (1970)
 
Infrared refractive index  3C-SiC   ~=2.55 300 K Goldberg et al.(2001)
   4H-SiC   ~=2.55 (c axis)
~=2.59 ( ||c axis)
300 K Goldberg et al.(2001)
   6H-SiC   ~=2.55 (c axis)
~=2.59 ( ||c axis)
300 K Goldberg et al.(2001)
 
Refractive index n(λ) 3C-SiC n(λ)~= 2.55378 + 3.417 x 104·λ-2   300K, 467nm < λ< 691nm Shaffer & Naum (1969)
  4H-SiC n0(λ)~= 2.5610 + 3.4 x 104·λ-2  
ne(λ)~= 2.6041 + 3.75 x 104·λ-2
300K, 467nm < λ< 691nm Shaffer & Naum (1971)
  6H-SiC n0(λ)~= 2.55531 + 3.34 x 104·λ-2
 ne(λ)~= 2.5852 + 3.68 x 104·λ-2
300K, 467nm < λ< 691nm Shaffer & Naum (1971)
      also see Refractive index n vs. wavelength and photon energy Shaffer & Naum (1971)
 
Radiative recombination coefficient 4H-SiC  
6H-SiC
1.5 x 10-12 cm3/s 300 K, estimation Galeskas et al. (1997)
Optical photon energy 3C-SiC   102.8 meV 300 K Goldberg et al.(2001)
4H-SiC   104.2 meV
6H-SiC   104.2 meV
 
Effective electron mass
      (longitudinal)ml
3C-SiC 0.68mo 300 K Son et al. (1994);
Son et al. (1995)
3C-SiC 0.677(15)mo 45K, Cyclotrone resonance Kaplan et al. (1985)
  4H-SiC 0.29mo 300 K Son et al. (1994);
Son et al. (1995)
  6H-SiC 0.20mo 300 K Son et al. (1994); Son et al. (1995)
 
Effective electron mass
      (transverse)mt
3C-SiC 0.25mo 300 K Son et al. (1994);
Son et al. (1995)
3C-SiC 0.247(11)mo 45K, Cyclotrone resonance Kaplan et al. (1985)
  4H-SiC 0.42mo 300 K Son et al. (1994);
Son et al. (1995)
  6H-SiC 0.42mo    
Effective mass of density of states  mcd 3C-SiC 0.72mo 300 K Son et al. (1994);
Son et al. (1995)
  4H-SiC 0.77mo    
  6H-SiC 2.34mo    
 
Effective mass of the density of states
in one valley of conduction band mc
3C-SiC 0.35mo 300 K Son et al. (1994);
Son et al. (1995)
  4H-SiC 0.37mo    
  6H-SiC 0.71mo    
 
Effective mass of conductivity  mcc 3C-SiC 0.32mo 300 K Son et al. (1994);
Son et al. (1995)
  4H-SiC 0.36mo    
  6H-SiC 0.57mo    
    Remarks Referens
Effective hall mass of density of state mv  3C-SiC 0.6 mo 300 K Son et al. (1994);
Son et al. (1995)
  4H-SiC ~1.0 mo 300 K  
  6H-SiC ~1.0 mo 300 K  
         
Lattice constant, 3C-SiC a=4.3596 A  297 K, Debye-Scherrer;
see also Temperature dependence
Taylor & Jones (1960)
  4H-SiC a = 3.0730 A 
b = 10.053
300 K Goldberg et al.(2001)
  6H-SiC a = 3.0730 A 
b = 10.053
297 K, Debye-Scherrer;
see also Temperature dependence
Taylor & Jones (1960)