AlN
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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)

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

 

hexagonal AlN in P63mc (186 ) space group
hexagonal AlN in P63mc (186 ) space group
hexagonal AlN in P63mc (186 ) space group
(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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