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In addition to group IV elements, compounds of group III and group V elements, and also compounds of group II and group VI elements are often semiconductors. The common feature to all of these is that they have an average of 4 valence electrons per atom.
One example of a compound semiconductor is gallium arsenide, GaAs. In a compound semiconductor like GaAs, doping can be accomplished by slightly varying the stoichiometry, i.e., the ratio of Ga atoms to As atoms. A slight increase in the proportion of As produces n-type doping, and a slight increase in the proportion of Ga produces p-type doping.
The table below list some semiconducting elements and compounds together with their bandgaps at 300 K.
| |
Material |
Direct / Indirect Bandgap |
Band Gap Energy at 300 K (eV) |
Elements |
C (diamond)
Ge
Si
Sn (grey) |
Indirect
Indirect
Indirect
Direct |
5.47
0.66
1.12
0.08 |
| Groups III-V compounds |
GaAs
InAs
InSb
GaP
GaN
InN |
Direct
Direct
Direct
Indirect
Direct
Direct |
1.42
0.36
0.17
2.26
3.36
0.70 |
| Groups IV-IV compounds |
α-SiC |
Indirect |
2.99 |
| Groups II-VI compounds |
ZnO
CdSe
ZnS |
Direct
Direct
Direct |
3.35
1.70
3.68 |
Data from R.E. Hummel, Electronic Properties of Materials, 3rd edition, Appendix 4, p. 413.
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