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

We have found experimental conditions for the growth of n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -SIPOS:p-Si heterojunction emitters with forward saturation current J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> = 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-14</sup> Amps/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> or equivalently "emitter Gummel number" G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</inf> = 3.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> s/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> . This outstanding figure of merit seems to rely upon the presence of a thin interfacial oxide between the SIPOS and the crystalline silicon. We invoke a model 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.