(Invited) Development of β-Ga₂O₃ Materials

Abstract

β-Ga 2 O 3 has attracted significant recent attention for its large bandgap of 4.8 eV which leads to a high breakdown electric field, predicted to be 8 MV/cm. With a predicted maximum bulk electron mobility of 300 cm 2 /Vs, β-Ga 2 O 3 yields a Baliga figure of merit (BFOM) that is higher than that of 4H-SiC and GaN. β-Ga 2 O 3 has a monoclinic crystal structure (usually represented with the b-axis as the unique axis) with strong anisotropy in physical properties. The crystal cleaves easily on the (100) and (201) planes. MBE growth on cleavage planes yields low growth rates due to a strong propensity for Ga loss via suboxides [M.-Y. Tsai et al. , J. Vac Sci. Tech. A 28 , 354 (2010).]. Growth on non-cleavage planes, such as (010), however, yields high growth rates [K. Sasaki et al ., J. Cryst. Growth 378 , 591 (2013).]. In this presentation, we review our work on development of growth of β-Ga 2 O 3 (010) by plasma-assisted MBE. We present the development of high temperature homoepitaxial growth of β-Ga 2 O 3 (010) and preliminary Sn doping [H. Okumura et al., Appl. Phys. Express 7 , 095501 (2014)]; the development of coherent β-(Al x Ga 1-x ) 2 O 3 /Ga 2 O 3 heterostructures [Kaun et al ., J. Vac. Sci. Tech. 33 , 041508 (2015)]; and viable RIE and ICP etch processes [J. Hogan et al., in preparation].