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.

DX-center energy calculation with quantitative mobility spectrum analysis in n-AlGaAs/GaAs structures with low Al content

“…In many studies, including ours, 2DEG dominant Hall carrier densities are slightly increased with increasing temperature due to the thermal activation of bulk carriers at the barrier or other bulkrelated layer [31,33,34]. After implementing QMSA method, 2DEG densities mostly show temperature independent behavior [22,26,33,35,36]. However, in this study, the 2DEG density extracted by QMSA is drastically decreased with increasing temperature.…”

SiC Substrate effects on electron transport in the epitaxial graphene layer

“…[12][13][14][15][16]18] Among these techniques, the quantitative mobility spectrum analysis (QMSA) method is the most popular. [14,15] The QMSA technique, which generates optimized quantitative results from the experimental results, can be effectively used for determining the individual carriers in multilayered semiconductors. [14,15] It has no limits for the carrier type and number of channels.…”

“…[14,15] The QMSA technique, which generates optimized quantitative results from the experimental results, can be effectively used for determining the individual carriers in multilayered semiconductors. [14,15] It has no limits for the carrier type and number of channels. However, in order to extract the effect of low mobility bulk carriers, very large magnetic fields (µ min B max >> 1) are required.…”

“…[12][13][14][15][16][17][18][19] In order to extract the correct transport parameters of the individual channel in the multilayered structure, such as GaAs/Al x Ga 1-x As and Al x Ga 1-x N/ GaN heterostructures, several extraction techniques were proposed. [12][13][14][15][16]18] Among these techniques, the quantitative mobility spectrum analysis (QMSA) method is the most popular. [14,15] The QMSA technique, which generates optimized quantitative results from the experimental results, can be effectively used for determining the individual carriers in multilayered semiconductors.…”

“…[9] Since the carriers in different conducting channels do not all have the same drift velocity, single magnetic field Hall measurements can only give an approximate result about the carriers in the multichannel conduction structures. [12][13][14][15][16][17][18][19] To extract the contributions of 2DEG conductivity in graphene layers and the parallel conduction in SiC substrate, the simple parallel conduction extraction method (SPCEM) can be used. [13,15,16] There may be an important parallel conducting channel even for the graphene layers and SiC substrate.…”