Quantitative measurements of recombination enhanced dislocation glide in gallium arsenide

Abstract

Effects of 30‐keV electron‐beam irradiation on dislocation glide were investigated for α‐ and β‐dislocations in bulk n‐GaAs single crystals by cathodoluminescence microscopy using a scanning electron microscope with a bending apparatus in it. At high temperatures above T_c, the electron irradiation has no effect on dislocation velocity v and the temperature dependence v(T) follows an Arrhenius formula v⁰_d exp(−E_d/kT). Below T_c, v(T) under irradiation breaks off the above relation and is enhanced following another Arrhenius formula v⁰_i exp(−E_i/kT). The enhancement effect is completely reversible for individual dislocations. From measurements of irradiation intensity I and stress τ dependences, the dislocation velocity was found to be expressed by a unified formula v=v⁰_d exp[−E_d(τ)/kT ]+v^*_i(I/I₀)^0.84 exp{−[E_d(τ)−ΔE]/kT}, which is explained by neither a heating effect nor a charge state effect, but the recombination enhanced defect motion (REDM) mechanism. In view of the REDM mechanism, the ΔE (∼0.7 eV for α‐dislocations and ∼1.1 eV for β‐dislocations) is related to the energy released upon a nonradiative recombination of generated excess carriers at the dislocations. Based on this postulation, the electronic energy states associated with dislocations are discussed in conjunction with previous, related studies.