Ballistic electron emission testing of semiconductor heterostructures

Abstract

In ballistic electron emission microscopy (BEEM) and spectroscopy, ballistic electrons are injected into a sample using a scanning tunneling microscope to probe the electrical properties of buried interfaces. In this communication, a method is proposed that uses the BEEM technique to observe the electron wave optical properties of semiconductor heterostructures. This method provides a three-terminal configuration for characterizing electron wave devices that overcomes many of the limitations encountered in other two- and three-terminal measurement techniques. Specifically, the method provides an injector, which is well isolated from the heterostructure, that injects a collimated beam of ballistic carriers with a precisely controlled energy distribution. These carriers accurately probe the quantum transmittance of a voltage-tunable electron wave interference structure, which can be designed with a light doping to minimize impurity and electron-electron scattering. A general procedure is presented for analyzing this experimental configuration based on a combination of the models used to describe BEEM and ballistic electron transport in semiconductors. Using this procedure, BEEM testing of an electron wave energy filter is modeled and clear quantum interference effects are predicted. This BEEM configuration should allow for the precise characterization of a wide range of ballastic electron transport effects such as quantum reflections from interfaces and electron wave interference effects, phenomena that are presently of wide interest.