Theoretical structural optimization of a GaAs pn or pin structured avalanche electron emitting diode

Abstract

In an avalanche electron emitting diode (AEED) the electrons are emitted after being accelerated in the internal electric field of a very shallow p-n (or p-i-n) junction biased in avalanche breakdown. Upon reaching the surface only those electrons having energies higher than the work function of the surface are emitted. The excess electrons are drained away through a thin surface channel. An attempt is made to find the structure and doping levels which maximize the efficiency (defined as the ratio of vacuum emitted current to total current through the junction). If one assumes a constant lambda for the lucky electrons independent of doping level, the proposed model predicts the highest efficiencies when using the maximum obtainable doping levels for the n-type top layer. For the same top doping level the p-i-n structure shows only a very small improvement over the p-n structure. If the effective mean free path depends on the doping level (specifically, for the intrinsic layer of the p-i-n structure), then there exists an optimum thickness of this intrinsic layer for obtaining maximum efficiency. >