A study of n+-SIPOS:p-Si heterojunction emitters

Experimental conditions for the growth of n(+)-SIPOS:p-Si heterojunction emitters with forward saturation current of 10 to the -14th Amps/sq cm, or equivalently, 'emitter Gummel number' of 3.3 x 10 to the 15th s/cm exp 4, have been found. This outstanding figure of merit seems to rely upon the presence of a thin interfacial oxide between the SIPOS and the crystalline silicon. A model is invoked in which majority-carrier (electron) contact is made by microcrystalline grains which protrude into the interfacial oxide, but minority-carrier (hole) recombination is inhibited by the small fractional area coverage of such contacts. The result is an emitter structure which is robust, and relatively insensitive to variations in processing conditions.