Theory of ballistic-electron-emission microscopy of buried semiconductor heterostructures

We extend the theoretical description of ballistic-electron-emission microscopy (BEEM) to the study of buried heterojunctions. We calculate the collector current and its first and second derivatives with respect to tip-base bias voltage for buried single-barrier and double-barrier resonant tunneling structures and show how they systematically vary with the parameters of the heterostructure. We show that the second derivative of the collector current is approximately a product of the heterostructure transmission coefficient and a slowly varying function of bias voltage. The calculated results are in good agreement with the first measurements of BEEM used to probe buried double-barrier heterostructures.