Layered transition metal dichalcogenides: promising near-lattice-matched substrates for GaN growth

TL;DR

This study demonstrates that layered transition-metal dichalcogenides can serve as near-lattice-matched substrates for GaN growth, enabling high-quality epitaxial layers with promising optical properties.

Contribution

It introduces layered transition-metal dichalcogenides as novel substrates for GaN epitaxy, showing successful growth and characterization of strain-free GaN layers.

Findings

Strain-free, single-crystal GaN islands grown on chalcogenide flakes

Strong near-band-edge emission observed in GaN layers

Feasibility of large-area GaN growth on CVD MoS2

Abstract

Most III-nitride semiconductors are grown on non-lattice-matched substrates like sapphire or silicon due to the extreme difficulty of obtaining a native GaN substrate. We show that several layered transition-metal dichalcogenides are closely lattice matched to GaN and report the growth of GaN on a range of such layered materials. We report detailed studies of the growth of GaN on mechanically-exfoliated flakes WS$_2$ and MoS$_2$ by metalorganic vapour phase epitaxy. Structural and optical characterization show that strain-free, single-crystal islands of GaN are obtained on the underlying chalcogenide flakes. We obtain strong near-band-edge emission from these layers, and analyse their temperature-dependent photoluminescence properties. We also report a proof-of-concept demonstration of large-area epitaxial growth of GaN on CVD MoS$_2$. Our results show that the transition-metal dichalcogenides can serve as novel near-lattice-matched substrates for nitride growth.