| 摘要 |
PURPOSE:To improve a high frequency characteristic by mutually stacking the P type first and second semiconductor layers, giving a larger energy gap to the first semiconductor layer and also giving a thickness through which electrons can pass by the tunnel effect. CONSTITUTION:A base 12 of bipolar transistor having an emitter 11 and a collector 13 is composed of P type layers 12A and 12B, an energy gap Eg is in the relation of EgA>EgB. Moreover, thickness of the layer 12A is as thin as allowing electrons to pass by the tunnel effect. Potential well is formed repeatedly in the conductive band of base. In the thermal equilibrium condition, electrons are not implanted to the base from the emitter, but when a forward bias is applied, electrons implanted to the base pass quickly through the layer 12A owing to the tunnel effect in such a speed as neglecting a running time and runs through the layer 12B by diffusion. In case, a number of repetitions of each layer is selected, a base expanding resistance and running time can be reduced, improving a high frequency characteristic. In addition, when a sum of Eg and affinity is made equal in both layers, the electron running time ca be more improved. |
