Growth of Highly Crystalline GaN at High Growth Rate by Trihalide Vapor‐Phase Epitaxy

Abstract

Free‐standing gallium nitride (GaN) wafers are being increasingly used for high‐power and high‐frequency electronic devices. However, these have to be produced at low costs while maintaining high quality. With the aim of reducing the cost of manufacturing GaN substrates, trihalide vapor‐phase epitaxy (THVPE) is investigated to explore the effect of growth temperatures up to 1400 °C. High growth rate and high crystal quality are achieved simultaneously using THVPE. High‐quality GaN crystals are obtained at the growth rate of more than 300 μm h−1. Crystal characteristics are confirmed via the full width at half maximum (FWHM) of the (002) plane, obtained by the X‐ray two‐crystal (XRC) method. Dark spot density (DSD) measured via cathode luminescence decreases to the level of seed substrate at growth temperatures above 1300 °C. The yellow emission band is not visible in the photoluminescence spectra of the 2 in.‐diameter sample, which is consistent with very small concentrations of carbon impurities in the crystal. In addition to the attainment of high‐purity materials, parasitic polycrystal growth around the wafer and the reactor wall is eliminated, which can improve the productivity of the THVPE, due to very little down time of the reactor.

Effects of pressure on GaN growth in a specific warm-wall MOCVD reactor

“…According to the reports, the origin of the YL band came from gallium vacancies, carbon impurities, edge dislocations, etc. 26,27 These impurities and structural defects might be harmful to optical and electronic devices. 28 The absence of the YL band in our samples mean that there were few deep acceptors of gallium vacancies, carbon impurities, or other acceptor defects in the GaN films grown by our warm-wall MOCVD system.…”

Suppression of cluster formation in GaN growth by tri-halide vapor phase epitaxy with external GaCl3 gas supply system

“…Then, the synthesized GaCl 3 or GaCl gas is mixed with NH 3 gas and transported to the crystal growth zone, resulting in epitaxial growth of GaN on a GaN seed wafer. The name HVPE is generally used for the method using monohalide GaCl, while THVPE [24][25][26][27][28] is used for HVPE growth using tri-halide GaCl 3 .…”