The general expressions on common emitter DC Current gain hFE
emitter Gummel number Ge and current gain enhancement factor K of polysilicon emitter transistor (PET) have been derived in the analytical forms for a complete structure of PET by considering various factors which affect the current gain of PETs. The various device structure of PETs can be unified in these general expressions
and according to these expressions
PETs with the different device structure are classified scientifically. These general expressions include Ning’s and Graaff’s theoretical results.