Composition behaviour of energy band gaps in the alloy AlxGayIn1–x–ySbzAs1–z

Abstract

The principal energy band gaps [E(), E(L), and E(X)] of the pentanary alloy are calculated over the entire composition space (x,y, and z) using the universal tight-binding method based on basis functions. As the compositions x,y, and z increase, increases rapidly and approaches E(X) or E(L). A direct-to-indirect transition occurs in the high-composition range of because of either E(X) or E(L). It is found that the direct band-gap energy ranges from 0.18 to 1.98 eV. The independent composition effects of x, y, and z in the band gaps are investigated and compared with experimental data, and the results are in good agreement. In addition, the energy band gaps of the alloy that were lattice matched on InAs and GaSb are found to be in the mid-infrared spectral range, which ranges from 0.35 to 0.57 eV (3.50–2.17 m) and 0.32 to 0.54 eV (3.88–2.29 m), respectively.