Magnetotransport in β-Ga2O3 Thin Films grown by MOCVD
Access to this document is restricted. Some items have been embargoed at the request of the author, but will be made publicly available after the "No Access Until" date.
During the embargo period, you may request access to the item by clicking the link to the restricted file(s) and completing the request form. If we have contact information for a Cornell author, we will contact the author and request permission to provide access. If we do not have contact information for a Cornell author, or the author denies or does not respond to our inquiry, we will not be able to provide access. For more information, review our policies for restricted content.
β-Ga2O3 is an ultra-wide bandgap semiconductor that has gained significant attention due to potential applications in high-voltage semiconductor devices owing to its bandgap of 4.8 eV. The expected high critical breakdown field (8 MV/cm) results in a high Baliga’s figure of merit (BFOM) that is approximately 3-10 times larger than that of SiC and GaN-based power electronic devices. Simultaneously, it also exhibits a high Johnson’s figure of merit (JFOM), indicating the material’s suitability for radio frequency (RF) applications, which exceeds that of semiconductors like GaAs and GaN. Furthermore, β-Ga2O3 offers excellent control over n-type doping ranging from 1015 cm−3 to 1020 cm−3. Furthermore, the availability of melt-grown single-crystal substrates, β-Ga2O3 is commercially viable for large-scale production. However, there are a few key hurdles to the development of practical Ga2O3-based electronic devices, such as its low room temperature electron mobility limited by polar optical phonon scattering. In this study, we investigated the electron transport phenomenon in uniform and delta-doped β-Ga2O3 thin films and modulation-doped β-(Al, Ga)2O3/Ga2O3 heterostructures grown by metalorganic chemical vapor deposition (MOCVD). Through detailed analysis of magnetotransport measurements, including temperature-dependent Hall and Shubnikov-de Haas (SdH) oscillations, we systematically characterize the two-dimensional electron gas (2DEG) formed at the heterointerface. The observation of SdH oscillations in 2DEG structures at low temperatures (T <10 K) indicates high material quality. Prior work by other groups have demonstrated molecular beam epitaxial (MBE) grown β-Ga2O3-based 2DEG structures exhibiting SdH oscillations. This study, for the first time, presents the observation of SdH oscillations in MOCVD-grown 2DEG structures. This will enable quantification of temperature dependence of transport scattering mechanisms that limit the electron mobility. Leveraging these measurements, future work will further optimize these 2DEG structures to enable high-performance β-Ga2O3 RF devices.