Two-Carrier Model-Fitting of Hall Effect in Semiconductors with Dual-Band Occupation: A Case Study in GaN Two-Dimensional Hole Gas

TL;DR

This paper introduces a two-carrier Hall effect model fitting algorithm to accurately analyze magnetotransport data in GaN 2D hole gases, revealing the coexistence of light and heavy holes and correcting previous misinterpretations of carrier density.

Contribution

The study develops a novel two-carrier fitting method that distinguishes light and heavy hole contributions in GaN 2DHGs, providing the first experimental evidence of light hole conduction in GaN.

Findings

Resolved light and heavy hole carrier densities consistent with simulations.

Observed light hole mobility of approximately 1400 cm²/Vs at 2 K.

First experimental detection of light hole conduction in GaN.

Abstract

We develop a two-carrier Hall effect model fitting algorithm to analyze temperature-dependent magnetotransport measurements of a high-density ($\sim4\times10^{13}$ cm$^2$/Vs) polarization-induced two-dimensional hole gas (2DHG) in a GaN/AlN heterostructure. Previous transport studies in GaN 2DHGs have reported a two-fold reduction in 2DHG carrier density from room to cryogenic temperature. We demonstrate that this apparent drop in carrier density is an artifact of assuming one species of carriers when interpreting Hall effect measurements. Using an appropriate two-carrier model, we resolve light hole (LH) and heavy hole (HH) carrier densities congruent with self-consistent Poisson-k$\cdot$p simulations and observe an LH mobility of $\sim$1400 cm$^2$/Vs and HH mobility of $\sim$300 cm$^2$/Vs at 2 K. This report constitutes the first experimental signature of LH band conductivity reported in GaN.