Variation of junction transistor current amplification factor with emitter current

A theory for the variation of the common emitter current amplification factor, β, of a junction transistor with emitter current is given in which the effects of emitter current variation are visualized directly in terms of the effects of variation of the injection level in the base. The use of several auxiliary functions of emitter current which previous authors have used in the development of the theory is avoided. In previous works, agreement between experimental and theoretical results required that the components of the boat current be present in a definite proportion. On the other hand. according to the present analysis, the proportion in which these components are present can have infinite variations and only the overall value of the base current, should be a particular function of the injection level in the base for a particular manner of variation of β with I e . The role previously assigned to surface recombination effects in the base to account for the initial increace of β with Ie needs reconsideration as it now turns out that this initial increace can exist even if surfheo recombination is completely absent.