Growth and Electrical Characterization of N-face AlGaN/GaN Heterostructures

Abstract

We describe growth and characterization of N-face GaN-based high electron mobility structures using plasma-assisted molecular beam epitaxy (MBE) on C-face SiC substrates. A two-step buffer approach consisting of a low Ga-flux followed by high Ga-flux was used to achieve smooth morphologies and threading dislocation (TD) densities as low as 1.5×10¹⁰ cm^-2. These TD densities are comparable to the lowest achieved on Ga-face GaN grown by MBE on Si-face SiC. Secondary ion mass spectrometry measurements were carried out to study O, C, and Si incorporation. Hall, capacitance–voltage and transfer length method measurements on GaN/AlGaN/GaN modulation-doped heterostructures were found to match simulations, and a charge of 1×10¹³ cm^-2 with electron mobility above 1000 cm² V^-1 s^-1 was measured.