Magnetic field dependent Hall data analysis of electron transport in modulation-doped AlGaN/GaN heterostructures

Abstract

Experimental magnetic field dependent Hall and resistivity data is presented for two modulation-doped AlGaN/GaN heterostructures in the temperature range from 6 to 300 K and for a magnetic field up to 12 T. The mobility and concentration of electrons within the two-dimensional electron gas (2DEG) at the AlGaN/GaN interface and within the underlying GaN layer are readily separated and characterized using quantitative mobility spectrum analysis. The observed transport parameters of the 2DEG are explained using the classical band theory for a degenerate electron gas. Analysis of the temperature dependencies of mobility and electron concentration in the GaN layer and 2DEG indicates that electron transport in the GaN layer is dominated by carriers in the conduction band for the case of low-doping (<1017 cm−3), and by conduction via an impurity band for highly doped material (>1018 cm−3). The simultaneous analysis of the multilayer AlGaN/GaN structure applied in this work renders the results applicable directly to modulation-doped field-effect transistors based on similar structures.