Influence of doping of Ga0.68Al0.32As on its cathodoluminescence and threshold current density of a laser pumped by an electron beam

A study was made of the influence of doping of Ga_0.68Al_0.32As solid solutions with tellurium (from 5×10¹⁶ to 1×10¹⁸ cm^–3) or zinc (from 4×10¹⁷ to 1×10¹⁹ cm^–3) on the radiative characteristics. The cathodoluminescence intensity and the threshold current density of an electron-beam-pumped laser deteriorated greatly as a result of doping with tellurium in amounts in excess of 3×10¹⁷ cm^–3. This was attributed to a nonradiative recombination channel in which an impurity level or a band associated with an indirect L minimum of the conduction band participated. In the case of zinc doping the cathodoluminescence intensity and the threshold current density of a laser were practically indepedent of the dopant concentration. The zinc-doped samples had a lower threshold current density (50 mA/cm² at T = 90 K and 0.9 A/cm² at T = 300 K) than the samples with n-type conduction.