Minority carrier effects in GaInP laser diodes

摘要

Using a top-contact window, we have observed emission from andirect-gap monitor layer placed at the interface between the p-claddingnand contact layers of an AlGaInP laser diode when driven under forwardnbias, thereby providing direct evidence for minority carrier (electron)nleakage in these devices. We have further shown that the leakage is duento both drift and diffusion and, using pulsed optical excitation of andevice under bias, we have determined a value of 170±10 cm2n V-1 s-1 for the mobility of minorityncarriers in the p-type cladding layer by a time-of-flight experiment.nThe data was analyzed using a simulation which takes account of theninfluence of recombination times in the well and monitor layer on thenoverall time response of the structure. The measured mobilityncorresponds to electron transport through the X-conduction band. We shownthat the drift component of the leakage current reduces the differentialnefficiency and is responsible for the decrease in external differentialnefficiency with increasing temperature. Because the leakage occurs by anmixture of drift and diffusion, the transit time does not decreasensignificantly with increasing drive current; however the impact ofnleakage on the modulation response is predicted to be very small unlessnthe leakage becomes a substantial fraction of the total current