SiC (Silicon Carbide)
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Crystalline silicon carbide (SiC) has structures of tetrahedrally coordinated lattice. The atomic layers can stack in cubic (C), hexagonal (H),or rhombohedral (R) configurations. These structures are labeled by the symmetry (C, H, or R) following the number of the layers in one period of the stacking sequence. Therefore, 3C is equivalent to the zincblende structure, while 2H is the wurtzite structure. The most common commercially available form is 6H-SiC (Table 2089a).

Figure 2089a shows bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices).

Bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices)

Figure 2089a. Bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices). Adapted from [1]

Table 2089a shows the lattice properties of 6H-SiC.

Table 2089a. Comparison of properties of crystalline and amorphous SiC materials.
Crystalline SiC
Amorphous SiC
Density (g/cm3)
3.217 for 6H-SiC
Bond Length (Å)
1.88 for 6H-SiC
Cohesive energy per bond
(Ecoh, eV)
3.17 for 6H-SiC
Lattice parameter (Å)
(wurtzite structure)
a = 3.081, c = 15.092, & c/a = 1.633 (x3) for 6H-SiC
a = 4.36
Energy gap/Optical band gap Eg (eV)
1.90 for a-Si1-xCx:H
Indirect bandgap (Eg,ind, eV)
  2.20
Urbach energy E0 (meV)
90 for a-Si1-xCx:H
Fermi level density of states g (EF) (cm-3eV-1)
  1017 for a-Si1-xCx:H
Miscibility with Si
<20%

Table 2089b shows the lattice mismatch (%) between the substrates and epitaxial layers, and the resulting misfit dislocation separation (in Å) corresponding to complete misfit relaxation for the basal plane interfaces.

Table 2089b. The lattice mismatch (%) between the substrate and epitaxial layers, and the resulting misfit dislocation separation (in Å).

Crystalline Properties
6H-SiC
α-A1203
InN
AlN
GaN
Lattice mismatch with
Sapphire
11.5%
--
25.4%
12.5%
14.8%
SiC
--
-11.5%
14.0%
1.0%
3.3%
GaN
-3.3%
-14.8%
10.6%
-2.4%
--
Dislocation distance on
Sapphire
21.9
--
10.6
20.3
17.2
SiC
--
21.9
20.4
276.7
80.9
GaN
80.9
17.2
27.3
114.4
--

Note that SiC normally has poor native oxides.

Figure 2089b shows the solubility for impurities in SiC.

Solubility for impurities in SiC

Figure 2089b. Solubility for impurities in SiC.

 

 

 

 

 

 

 

 

[1] Ponce, F. A. and Bour, D.P., Nature, 386, (1997) 351.

 

 

 

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