Metal contact double injection in GaAs

Recent studies on the GaAs injection laser have indicated certain problems associated with the localization of the region of population inversion to the immediate vicinity of the p-n junction. It has also been pointed out that very heavy doping is necessary of laser action. However, in heavily doped material the absorption of light is large, raising the threshold current for laser action. These problems can be overcome simultaneously by using a metal-GaAs-metal structure operating in the double injection mode described by Lampert. A metal of low work function is used to inject electrons at one surface and one of high work function to inject holes at the opposite surface. When sufficient double injection occurs to neutralize the bulk between the electrodes, the voltage required to sustain the current drops to a low value.