Minority carrier effects in GaInP laser diodes

Using a top-contact window, we have observed emission from a direct-gap mon itor layer placed at the interface between the p-cladding and contact layer s of an AlGaInP laser diode when driven under forward bias, thereby providi ng direct evidence for minority carrier (electron) leakage in these devices . We have further shown that the leakage is due to both drift and diffusion and, using pulsed optical excitation of a device under bias, we have deter mined a value of 170+/-10 cm(2)V(-1)s(-1) for the mobility of minority carr iers in the p-type cladding layer by a time-of-flight experiment. The data was analyzed using a simulation which takes account of the influence of rec ombination times in the well and monitor layer on the overall time response of the structure. The measured mobility corresponds to electron transport through the X-conduction band. We show that the drift component of the leak age current reduces the differential efficiency and is responsible for the decrease in external differential efficiency with increasing temperature, B ecause the Leakage occurs by a mixture of drift and diffusion, the transit time does not decrease significantly with increasing drive current; however , the impact of leakage on the modulation response is predicted to be very small unless the leakage becomes a substantial fraction of the total curren t.