Commercial and Non-Commercial
Semiconducting Light-emitting Diodes (LEDs)
- Practical Electron Microscopy and Database -
- An Online Book -

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This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.
 

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All the commercial semiconducting light-emitting diodes (LEDs) and laser diodes (LDs) are currently made of III-V compound thin films produced by the metalorganic chemical vapor deposition (MOCVD) technique. These III-V compounds can be grouped into the families of the antimonides, arsenides, phosphides and nitrides. The first three have mainly a cubic lattice structure, while the nitrides have a hexagonal lattice structure.

The materials in LEDs need superior electronic properties and high light emission efficiencies by eliminating the crystalline perfection such as stacking faults and dislocations. Defect degradation in LEDs is dominated by the motion of dislocations in the active region with the creation of the so-called dark-line defects.

Figure 2244 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 2244. Bandgap and chemical bond length for semiconductors used in visible LEDs (light emitting devices). Adapted from [1]

Table 2244 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 2244. 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
--

 

 

 

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

 

 

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