Аннотация:The multiband approximation and the effective mass method are used to calculate the coefficient representing the passage of a quasiparticle above a symmetric rectangular quantum well. A calculation is reported of the current-voltage characteristic of a transistor structure with a unipolar conductivity and containing a deep rectangular quantum well. The current-voltage characteristic is shown to have falling regions both under space-charge-limited current conditions and in the emitter saturation regime.