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