The optical energy gap dependence on both carrier concentration and intrinsic energy gap in n-type semiconductors

Abstract

Burstein and Moss formulas were used to calculate the optical energy gaps for five n-type compound semiconductors. The room-temperature intrinsic energy gaps were found to increase from 2% for ZnO to about 7 times of its value for InSb. The room temperature critical Burstein point of carrier concentration n m for five compounds of InSb, InAs, GaAs, CdO and ZnO were found to be 0.27×10 18, 0.67×10 18, 3.0×10 18, 8.5×10 18 and 20×10 18 cm −3, respectively and the empirical relation E gi=4×10 −13×( n m) 0.6737 was found, where n m in cm −3 and E gi in eV. The latter relation gives the room temperature intrinsic energy gap for the compounds InP, GaSb and CdGeAs 2 to be 1.18 eV, 0.75 eV and 0.45 eV, respectively. A general empirical relation was also found for the dependence of the change of the optical energy gap of semiconductors on both their intrinsic energy gap and their carrier concentration.