Cathodoluminescence of n-Type GaAs

Abstract

n‐type GaAs specimens with carrier concentration in the range of 4×10¹⁶ to 6.8×10¹⁸ cm⁻³ were bombarded with 24‐kV electrons at 4.2°K. The emission spectrum indicates that the radiative transition occurs between donors and residual acceptor states. A simple phenomenological model suggests that most of the donor states are located below the Fermi level. Taking the bottom of a parabolic distribution of states in the conduction band as a reference, the maximum density of donor occurs roughly one‐third of the way to the Fermi level, this Fermi level being already depressed by the tail of states of the conduction band. The same model indicates that the width of the donor band varies as the one‐third power of the donor concentration.