Negative Resistance in Chromium-Doped GaAs p-i-n Diodes

Gallium arsenide p-i-n diodes, made by diffusing chromium and zinc into n-type material, exhibit a stable current-controlled negative resistance at room temperature and emit recombination radiation when biased in the forward direction. The current-voltage characteristics have been measured and analysis of the results shows that the negative resistance arises as a result of the emission of light at the p-i junction, this light being reabsorbed in the semi-insulating region and causing a photoconductive effect. The electron lifetime in the chromium-diffused semi-insulating region is estimated to be about 10−8–10−7 sec and diodes with a suitable zinc diffusion have an internal efficiency for light emission of about 0.1 photons per electron.