Adsorption-Controlled Growth of Ga2O3 by Suboxide Molecular-Beam Epitaxy

TL;DR

This paper presents a novel suboxide molecular-beam epitaxy (S-MBE) technique for high-rate, high-quality Ga2O3 growth, overcoming previous kinetic limitations and enabling advanced device applications.

Contribution

Introduction of S-MBE for Ga2O3, achieving growth rates over 1 μm/hr with excellent crystallinity and low-temperature processing, surpassing existing methods.

Findings

Achieved Ga2O3 growth rates up to 1.6 μm/hr.

Produced phase-pure, smooth, high-purity Ga2O3 films thicker than 4 μm.

Demonstrated applicability of S-MBE to various oxides.

Abstract

This paper introduces a growth method---suboxide molecular-beam epitaxy (S-MBE)---which enables the growth of Ga2O3 and related materials at growth rates exceeding 1 micrometer per hours with excellent crystallinity in an adsorptioncontrolled regime. Using a Ga + Ga2O3 mixture with an oxygen mole fraction of x(O) = 0.4 as an MBE source, we overcome kinetic limits that had previously hampered the adsorption-controlled growth of Ga2O3 by MBE. We present growth rates up to 1.6 micrometer per hour for Ga2O3--Al2O3 heterostructures with unprecedented crystalline quality and also at unparalleled low growth temperature for this level of perfection. We combine thermodynamic knowledge of how to create molecular-beams of targeted suboxides with a kinetic model developed for the S-MBE of III-VI compounds to identify appropriate growth conditions. Using S-MBE we demonstrate the growth of phase-pure, smooth, and high-purity homoepitaxial Ga2O3 films that are thicker than 4 micrometer. With the high growth rate of S-MBE we anticipate a significant improvement to vertical Ga2O3-based devices. We describe and demonstrate how this growth method can be applied to a wide-range of oxides. S-MBE rivals leading synthesis methods currently used for the production of Ga2O3-based devices.