Semiconductor Band Gaps

From the band theory of solids we see that semiconductors have a band gap between the valence and conduction bands. The size of the band gap has implications for the types of applications that can be made. A low band gap implies higher intrinsic conduction, and a high band gap implies a larger possible photon energy associated with a transition across the gap in light emitting diodes. Band gaps in electron volts are given for a few semiconductor materials in the table below.

Material
Band gap in eV
PbSe
0.27
PbTe
0.29
PbS
0.37
InN
0.67*
Ge
0.67
GaSb
0.7
Si
1.11
InP
1.35
GaAs
1.43
CdTe
1.58
AlSb
1.6
CdSe
1.73
AlAs
2.16
ZnTe
2.25
GaP
2.26
CdS
2.42
AlP
2.45
ZnSe
2.7
SiC
2.86
GaN
3.4
ZnS
3.6
Diamond
5.5
AlN
6.2*

* InN, GaN, and AlN are currently under study at Georgia State University. Other values are from Streetman and Banerje. The value for InN is not considered to be as well determined as those for the others, but illustrates that the band gap energies stretch from the near infrared to the ultraviolet. AlN, having a band gap greater than that of diamond, is a good insulator. GaN has been used for the production of blue LEDs.

Another band gap table
Closer look at bandsBand gap dependence on interatomic spacing
Index

Semiconductor concepts

Semiconductors for electronics

Reference
Streetman & Banerjee
 
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