Near band-edge luminescence of semi-insulating undoped gallium arsenide at high levels of excitation

TL;DR

This study investigates how near band-edge photoluminescence in semi-insulating undoped GaAs varies with impurity concentration and excitation level at 77K, revealing effects of impurity fluctuations and localized states.

Contribution

It provides new insights into the dependence of photoluminescence features on impurity levels and excitation, explaining the role of impurity-induced density tails and localized states.

Findings

Dependence of luminescence maximum and width on impurity concentration and excitation.

Formation of density tails due to impurity fluctuations.

Reduced many-particle interactions with increasing excitation level.

Abstract

The dependences of the maximum and the half-width of near band-edge photoluminescence of semi-insulating undoped GaAs crystals at 77K on the concentration of background acceptor impurities and the level of excitation in the range from 3x1021 to 6x1022 quantum/(cm2/s) are investigated. The observed dependences are explained by formation of the density tails of states as a result of fluctuations of impurity concentration and participation of localized states of the donor impurity band in radiative transitions. Reduction of many-particle interaction at increasing of N can be connected with increasing of shielding of charge carriers by atoms of impurity.