TABLE OF CONTENTS We will now examine special features of some semiconductors. Of particular interest are the bandedge properties since they dominate the transport and optical properties. In this context, it is important to appreciate the range of energies away from the band-edges which control various physical properties of devices. These energies are shown in Table 2.2 for various kinds of electronic and optical devices. As can be seen, the region of interest varies depending upon the kind of devices one is interested in. Bandedge properties are often captured by density of states (number of allowed states per unit volume per energy interval). This concept is reviewed in Appendix C.
| Devices | Region of Bandstructure of Importance Measured from Bandedge |
|---|---|
| Transistors (Source Gate) Low Field Region | ~ 2 k BT (~ 50 meV at T = 300 K) |
| Transistors High Field Region (Gate-Drain Region) | ~ 0.5 eV |
| Power Transistors Avalanche Detectors and Other Devices Involving Breakdown | ~ E gap ~ 1.0 eV |
| Lasers | ~ 2 - 3 k BT (~ 50 - 75 meV at T = 300 K) |
| Detectors | Variable, depending upon photon wavelength |
Silicon forms the backbone of modern electronics industry. The bandstructure of silicon is shown in Fig. 2.16 and, as can be seen, it has an indirect bandgap. This fact greatly limits the applications of Si...
