Question

Indium Gallium Arsenide is a compound semiconductor with a controllable composition. It has the chemical formula of InxGa1-xAs. The parameter x can vary between 0 and 1 (0 ≤ x ≤ 1). Irrespective of the value of x, the atomic ratio of (InxGa1-x) to As is 1. The room-temperature bandgap energy of GaAs is 1.39 eV, and that of InAs is 0.33 eV.

A. Draw well-labeled, schematic, energy-band diagrams characteristic of GaAs and InAs.

B. Calculate the maximum wavelength of electromagnetic radiation (i.e. light, but not necessarily visible light) that can be transmitted by GaAs and by InAs.

C. Briefly explain why wavelengths shorter than those you calculate are not transmitted.

D. If the gap energy is linearly related to composition, what gap energy would you expect for (In0.5Ga0.5)As?