An analysis of the effects of interface recombination on the transient response of double heterojunction devices

An exact transient solution is presented for the spatial and temporal variation of the injected minority carrier distribution and for the total number of injected minority carriers in a double heterojunction device, e.g., a light-emitting diode (LED) or diode laser, in the presence of interface recombination centers at the heterojunction boundaries, with finite minority carrier lifetime in the center region, and for current pulse excitation. The solution for the model assumed is completely general and can be applied to any material or dimensional situation; for purposes of illustration, numerical results appropriate for typical III-V or Pb-salt heterostructures are presented. It is shown that for the total number of injected minority carriers, an effective minority carrier lifetime can, in certain cases, be defined which is a function of the interfacial recombination centers, the minority carrier lifetime, and the middle or "active" region width. The practical implications of this and other results for device performance and analysis are discussed.