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Figure 2096a 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)](image1/4636.jpg)
Figure 2096a. Bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices). Adapted from [1]
Table 2096a shows the lattice properties of AlN.
Table 2096a. The lattice properties of AlN.
Crystalline properties |
|
|
Crystalline properties |
|
Lattice parameter (wurtzite structure) |
a = 3.1114 Å, c = 4.9792 Å, c/a = 1.6; α = 90°, β = 90°, γ = 120°. |
|
Bond Length (Å) |
1.89 |
|
Thermal expansion coefficient (x10-6C-1) |
a = 4.2 |
|
c = 5.3 |
Lattice parameter (Å)
(zincblende structure) |
a = 4.38 |
|
Density (g/cm3) |
3.26 |
Energy gap (eV) at 300K (for wurtzite W, & zincblende Z lattices) |
W = 6.2 D |
|
Cohesive energy per bond (Ecoh, eV) |
2.88 |
Z = 5.1 D |
|
Melting entropy (cal mol-1K-1) |
16.61 |
Melting temperature (TM, K) |
3487 |
|
Melting enthalpy (Kcal mol-1) |
57.92 |
Vapor pressure at TM (bar) |
30 |
|
|
|
Table 2096b 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 2096b. 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 |
-- |
Table 2096c. Magnitudes of Burgers vectors of dislocations in nitride semiconductors (in Å).
Burgers vectors |
InN |
AlN |
GaN |
a = 1/3 <1-210>
|
3.545
|
3.111
|
3.186 |
c = [0001]
|
5.703
|
4.979 |
5.178 |
c + a = 1/3 <11-23>
|
6.715
|
5.871
|
6.080 |
|
|
|
(a) [100] |
(b) [010] |
(c) [001] |
Figure 2096b. Simulated electron diffraction patterns of hexagonal AlN in P63mc (186 ) space group.
[1] Ponce, F. A. and Bour, D.P., Nature, 386, (1997) 351.
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