New technique for identification of deep-level trap emission to indirect conduction minima in GaAs

A new analysis of the C-V characteristics of the depletion region of a Schottky barrier in the presence of deep-level traps is presented which yields the absolute position of the energy level in the energy band diagram. It is found that for the commonly observed 0.830±0.005 eV electron trap in VPE GaAs, the level is located at 0.543 eV (240 K) and 0.537 eV (120 K) below the Γ conduction minimum. It is shown that this level emits electrons to the L minima and, that relative to these minima, exhibits a zero temperature coefficient. The capture cross section for this center is σ∞= (1.8±0.4) ×10−14 cm2 and has a zero activation energy over the temperature interval 120–240 K.