Abstract: The invention presents a structure of heterostructure-emitter and heterostructure-base transistor. The device structure are, from bottom upward in succession, a substrate, a buffer layer, a collector layer, a base layer, a quantum well, an emitter layer, a confinement layer and an ohmic contact layer. Of them, except the quantum well which is made of InGaAs and the confinement layer which is formed by AlGaAs, the rest are all made of GaAs material. Base on the design of the heterostructure of base and emitter, a transistor of such structure, under normal operation mode, possesses high current gain and low offset voltage so as to reduce undesirable power consumption. In addition, under the inverted operation mode, the interesting multiple S-shaped negative-differential-resistance may be obtained due to the avalanche multiplication and two-stage carrier confinement effects.