Tunnel Current Features Caused by Defect Assisted Process in Resonant-Tunnelling Structures

Abstract

Practically, all resonant-tunnelling devices contain as their important part an undoped spacer layer separating a heavily-doped layer from the barrier. Including the spacer layer into the structure has several good points. It permits, for instance, to decrease the device capacitance, to prevent impurity diffusion into the active part of the device, to eliminate an effect of the long-range Coulomb potential on the tunnelling, and thus, to improve the current-voltage characteristics of the device. however, a thick spacer layer is also a drawback which can essentially affect the transport properties in the injector. Actually, owing to a light doping in a close vicinity of the emitter barrier, an applied bias voltage creates an accumulation layer. Generally, the presence of the accumulation layer makes the tunnelling dynamics worse, because the recharging processes which occur in this layer are slow as compared with the tunnelling time thus giving rise to an extra frequency cut-off. The physical processes occurring in the injector part of device are still of interest as being of a large significance for the device operation. In this work we grew a structure whose composition was chosen so as to obtain the flat band regime in the emitter spacer under resonance condition. High