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

We develop a two-carrier Hall effect model fitting algorithm to analyze temperature-dependent magnetotransport measurements of a high-density ($\sim 4\times {10}^{13}$ 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.