Cornell Ultrawide Bandgap Oxide Electronics Group

Oxide semiconductors have been the mainstay in large-area thin-film transistors (TFTs) used in displays and touch screens. Some perovskite oxide semiconductors have shown promise for high performance electronics. Recently, the ultrawide bandgap semiconductor family of gallium oxide has emerged as an attractive material for power electronics and high voltage devices. We investigate the material epitaxy, doping, conductivity, electronic bandstructure and heterostructure control, and fabricate and measure the device performance limits of these oxide semiconductors. We co-design the thermal aspect with careful measurements of thermal conductivity of bulk and heterostructures.

Our papers in this area in chronological order

2022

373 JAP Tight-binding band structure of beta- and alpha-phase Ga2O3 and Al2O3

370 APL Infrared-active phonon modes and static dielectric constants in alpha-(AlGa)2O3 alloys

369 Phys. Rev. Applied Extending the kinetic and thermodynamic limits of MBE utilizing suboxide sources or metal-oxide catalyzed epitaxy

367 PSS(a) Photoelectric generation coefficient of beta-Ga2O3 during exposure to high-energy ionizing radiation

366 JAP A unified thermionic and thermionic-field emission model for ideal Schottky reverse-bias leakage current

365 Phys. Rev. Materials Infrared dielectric functions and Brillouin zone center phonons of alpha-Ga2O3 compared to alpha-Al2O3

2021

360 IEEE TED Breakdown mechanisms in beta-Ga2O3 trench-MOS Schotty barrier diodes

350 IEEE TED On-resistance of Ga2O3 trench-MOS Schottky-barrier diodes: Role of sidewall interface trapping

349 APL Materials Gamma-phase inclusions as common structural defects in alloyed beta-(AlGa)2O3 and doped beta-Ga2O3 films

348 Phys. Rev. Research Ultrafast dynamics of gallium vacancy charge states in beta-Ga2O3

344 APL Thermal stability of epitaxial alpha-Ga2O3 and (AlGa)2O3 layers on m-plane sapphire

342 APL Materials Adsorption-controlled growth of Ga2O3 by sub-oxide molecular-beam epitaxy

341 APL High-frequency and below bandgap anisotropic dielectric constants in alpha-(AlxGa1-x)2O3 (0<x<1)

338 Science Advances Crystal orientation dictated epitaxy of ultrawide bandgap 5.4-8.6 eV alpha-(AlGa)2O3 on m-plane sapphire

336 APL Anisotropic dielectric functions, band-to-band transitions, and critical points in alpha-Ga2O3

2020

331 DRC Very High Parallel-Plane Surface Electric Field of 4.3 MV/cm in Gallium Oxide Schottky Barrier Diodes with PtOx Contacts

328 APL Thermionic emission or tunneling? The universal transition electric field for ideal Schottky reverse leakage current: a case study in beta-GaOx

322 TED Guiding Principles for Trench Schottky Barrier Diodes Based on Ultrawide Bandgap Semiconductors: A Case Study in Ga2O3

321 TED Trapping and De-Trapping Mechanisms in beta-Ga2O3 Vertical FinFETs Investigated by Electro-Optical Measurements

318 APL Intra- and Inter-Conduction Band Optical Absorption Processes in beta-Ga2O3

310 APL Near-ideal reverse leakage current and practical maximum electric field in beta-Ga2O3 Schottky barrier diodes

303 APL Multiferroic LuFeO3 on GaN by MBE

2019

292 IEDM Single and multi-fin normally-off Ga2O3 vertical transistors with a breakdown voltage over 2.6 kV

290 EDL Field-Plated Ga2O3 Trench Schottky Barrier Diodes with a BV2/Ronsp of up to 0.95 GW/cm2

278 APL Significantly reduced thermal conductivity in beta-AlGaO/GaO superlattices

276 APL Materials Self-assembly and properties of domain walls in BiFeO3 layers grown via molecular-beam epitaxy

270 APEX Fin-channel orientation dependence of forward conduction in kV-class Ga2O3 trench Schottky barrier diodes

2018

264 APL Measurement of ultrafast dynamics of photoexcited carriers in β-Ga2O3 by two-color optical pump-probe spectroscopy

263 IEDM 2.44 kV Ga2O3 vertical trench Schottky barrier diodes with very low reverse leakage current

260 APL 1230 V β-Ga2O3 trench Schottky barrier diodes with an ultra-low leakage current of <1 μA/cm2

259 APL Breakdown mechanism in 1 kA/cm2 and 960 V E-mode β-Ga2O3 vertical transistors

258 DRC 1.5 kV Vertical Ga2O3Trench-MIS Schottky Barrier Diodes

251 EDL Enhancement-Mode Ga2O3 Vertical Transistors With Breakdown Voltage >1 kV

247 TED Steep Sub-Boltzmann Switching in AlGaN/GaN Phase-FETs With ALD VO2

2017

244 Adv. Elect. Mat. Ultrawide Bandgap Semiconductors: Research Opportunities and Challenges

242 DRC Vertical fin Ga2O3power field-effect transistors with on/off ratio >10^9

235 APL Materials Adsorption-controlled growth of La-doped BaSnO3 by molecular-beam epitaxy

225 JJAP ICP-RIE etching of single-crystal beta-Ga2O3

2016

217 DRC Vertical Ga2O3Schottky barrier diodes on single-crystal β-Ga2O3(−201) substrates

214 APL Intrinsic electron mobility limits in beta-Ga2O3

209 APL Large electron concentration modulation using capacitance enhancement in SrTiO3/SmTiO3 Fin-FETs

2015

197 APL Ferroelectric transition in compressively strained SrTiO3 thin films

194 Phys. Rev. B Determination of the Mott-Hubbard gap in GdTiO3

188 APL Anisotropic Thermal Conductivity in Single-Crystal beta-Gallium Oxide

2014

167 Phys. Rev. Lett. Intrinsic Mobility Limiting Mechanisms in Strontium Titanate

165 APL High-Voltage Field-Effect Transistors with Wide-Bandgap Ga2O3 Nanomembranes