メサ型トランジスタの遮断周波数のエミッタ電流依存性

抄録

The phenomenon of the decrease in cutoff frequency of mesa-transistors at high injection level is investigated in detail. The emitter current dependence of cutoff frequency is expressed by the experimental formula
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where I₀ is the characteristic current and η the index of rapidity of the decrease. The dependence of these parameters on the collector resistivity is given. In the case of mesa-transistors, the mechanism of the decrease in cutoff frequency can not be accounted for by the decrease in the effective mobility of minority carrier but by the saturation of current density in the collector region.
It is also pointed out that the optimum collector resistivity can be determined if this phenomenon is taken into account.