Measuring the signature of bias and temperature-dependent barrier heights in III-N materials using a hot electron transistor

Abstract

We present a measurement technique to study barrier height inhomogeneity (BHI) in III-N materials. This technique is enabled by a hot electron transistor (HET), a vertical, unipolar device that works by injecting hot electrons over the emitter barrier and into a very thin base layer. After traversing the base, high energy electrons surmount the collector barrier and contribute to the collector current while low energy electrons reflect off the collector barrier and become the base current. The prevailing theory of BHI prescribes the replacement of a constant emitter barrier height with one that depends on both bias and temperature (i.e. ). Because the magnitude of the collector current is a strong function of the emitted electron energy and, therefore, the emitter barrier height, measuring the change in collector current with emitter bias and temperature allows us to determine the dependence of on these quantities. This advance will help provide a more thorough understanding of the physical sources of BHI in the III-Ns and assist in the diagnosis of key device nonidealities.