Hot carrier effects in double injection phenomena

Carrier heating is shown to be responsible for unusualI(V) characteristics observed in small-sizep⁺nn⁺ silicon on sapphire (SOS) devices. The classical quadratic law of the semiconductor regime becomes linear for high fields. The influence of dimensions and doping is experimentally checked and a model, based on the regional approximation method, is proposed. The key role is assumed by the hot-carrier region, growing from the cathode, where the electron and hole mobilities are field dependent: µ~E^–. A full agreement with the experiment in SOS is found for=0.5. The operating of hot carrierp⁺nn⁺ devices can be described concretely with usual formalism by using the concept of effective carrier mobilities, which depend on the applied voltage.