Cornell Electron Devices Society (EDS) presents:

Jonathan McCandless
Jena-Xing Group
Cornell University

Doping and Transport in Gallium Oxide

Abstract
Since the seminal work by Higashiwaki et al., in 2012, β-Ga2O3 has gained attention due to its large bandgap (~4.7 eV), the availability of large-area native substrates, and the ability to achieve multi-order electrical conductivity change through n-type doping.(1) The large bandgap and corresponding large critical field strength make it particularly appealing for high-power and high frequency applications. Additionally, Ga2O3 is polymorphic. The metastable α-phase – which take on the corundum structure – is of interest due to its larger intrinsic bandgap (~5.2 eV) and the ability to readily alloy it with Al – surpassing AlN (6.2 eV) – reaching bandgaps up to 8.8 eV.

Molecular beam epitaxy (MBE) is a growth technique which can form sharp interface and control single atomic layers of atoms, making this particularly suited for the growth of quantized heterostructures. Despite the benefits of MBE, there are several challenges in Ga2O3 growth. The growth kinetics and thermodynamics of MBE result in doping challenges for both the β- and α-phases. Additionally, the growth of α-Ga2O3 is challenging due to the metastability of the phase and the tendency of it to revert to the monoclinic β-phase.(2) In this talk, I will introduce and motivate Ga2O3 and will discuss my efforts in the stabilization and doping of both the α- and β- phases.(3)

1 M. Higashiwaki et al., APL, 100, 013504 (2012)
2 J. P. McCandless et al., APL, 119, 062102 (2021)
3 J. P. McCandless et. al., APL, 121, 072108 (2022)

Bio
Jon McCandless is a 6th year PhD candidate in electrical engineering, studying MBE growth and transport of Ga2O3 and related alloys. He is a 2019 recipient of the NSF Graduate Research Fellowship (GRFP) and an Irwin Jacobs Family Fellow. In 2021, Jon received a German Academic Exchange Service (DAAD) Fellowship to study polarization induced electron transport in Nitride heterostructure at the University of Bremen, Germany. His work has been featured by the editors in Applied Physics Letters, and he won the Best Student Presentation Award at the 2021 Electronic Materials Conference (EMC). Jon has authored or co-authored 13 refereed papers and 24 conference abstracts. His work has been published in Applied Physics Letters, Physical Review journals, and IEEE Electron Device Letters. Prior to Cornell, Jon worked at the Air Force Research Laboratory (AFRL) focusing on device fabrication and testing of GaN and Ga2O3 devices, and he is currently a member of the ACCESS Center – a joint center between AFRL and Cornell devoted to Ga2O3. Jon earned his BS in Engineering Physics, and a BSE in Electrical Engineering from Case Western Reserve University in 2016.