Cornell Ultrapolar and Ferroelectric Semiconductors Group

The high spontaneous and piezoelectric polarization in nitride semiconductors were discovered in late 1990s. The implications of polarization fields in nitride semiconductor heterostructures developed at several places including at Cornell University led to the success story of GaN HEMTs for high speed electronics and for power electronics. In 2009, it was discovered that AlScN can boast a piezoelectric coefficient that is nearly 400% higher than AlN, and in 2019 it was discovered that AlScN is ferroelectric. The nitride semiconductors therefore offer an exciting playground for studying the interaction of strong electronic polarization in semiconductors, and its many exciting device applications. At Cornell, a small and close-knit team is exploring the science and technological applications of very high polarization in semiconductors and enabling new applications in electronics, photonics, and quantum technologies.

Our papers in this area in chronological order

2022

372 APL Epitaxial ScAlN on GaN exhibits attractive high-K dielectric properties

371 APL Distributed polarization-doped GaN p-n diodes with near-unity ideality factor and avalanche breakdown voltage of 1.25 kV

364 Adv. Elect. Mat. Very high density (>1e14/cm2) polarization-induced 2D hole gases observed in undoped pseudomporphic InGaN/AlN heterostructures

363 APL Quantitative scanning microwave microscopy of 2D electron and hole gases in AlN/GaN heterostructures

2021

359 APEX Influence of collector doping setback in the quantum transport characteristics of GaN/AlN resonant tunneling diodes

358 IEEE ICSAF Towards realizing low coercive field operation of sputtered ferroelectric AlScN

357 DRC Large-signal response of AlN/GaN/AlN HEMTs at 30 GHz

355 IEEE ISAF Temperature-dependent Lowering of Coercive Field in 300 nm Sputtered Ferroelectric AlScN

353 APL Polarization-induced 2D hole gases in pserudomorphic undoped GaN/AlN heterostructures on single-crystal AlN substrates

347 SST Next-generation electronics on the ultrawide-bandgap aluminum nitride platform

345 JAP High-conductivity polarization-induced 2D hole gases in undoped GaN/AlN heterojunctions enabled by impurity blocking layers

343 APL Materials Strong effect of scandium source purity on chemical and electronic properties of epitaxial ScAlN/GaN heterostructures

337 PSSR Electric Fields and Surface Fermi Level in Undoped GaN/AlN 2D Hole Gas Heterostructures

333 JEDS First RF Power Operation of AlN/GaN/AlN HEMTs with >3 A/mm and 3.3 W/mm at 10 GHz

2020

332 IEDM GaN/AlN p-channel HFETs with Imax>420 mA/mm and ~20 GHz fT/fmax

327 Optics Express Distributed-feedback blue laser diode utilizing a tunnel junction grown by plasma-assisted molecular beam epitaxy

326 APL N-Polar GaN/AlN Resonant Tunneling Diodes

324 TED Prospects for Wide-Bandgap and Ultra-Wide-Bandgap CMOS Devices

323 TED Impact of Residual Carbon on Avalanche Voltage and Stability of Polarization-Induced Vertical GaN p-n Junction

319 APL Structural and Piezoelectric Properties of ultra-thin ScAlN Films grown on GaN by Molecular Beam Epitaxy

317 APL Light-Emitting Diodes With AlN Polarization-Induced Buried Tunnel Junctions: A Second Look

316 APL Bottom Tunnel Junction Blue Light-Emitting Field-Effect Transistors

308 PSS(a) All-Epitaxial Bulk Acoustic Wave Resonators

306 PSS(b) Oxygen Incorporation in the MBE growth of ScGaN and ScAlN

304 Phys. Rev. Applied Fighting Broken Symmetry with Doping: Towards Polar Resonant Tunneling Diodes with Symmetric Characteristics

303 APL Multiferroic LuFeO3 on GaN by MBE

302 APL Gallium nitride tunneling field-effect transistors exploiting polarization fields

299 PSS(b) MBE growth of large-area GaN/AlN 2D hole gas heterostructures

295 Optics Express Enhanced injection efficiency and light output in bottom tunnel-junction LEDs

2019

293 IEDM GaN/AlN Schottky-gate p-channel HFETs with InGaN contacts and 100 mA/mm on-current

285 TED Breakdown Walkout in Polarization-Doped Vertical GaN Diodes

284 APL MBE growth of ScN on hexagonal SiC, GaN, and AlN

283 Science A polarization-induced 2D Hole Gas in undoped Gallium Nitride Quantum Wells

282 ECS Trans. GaN-Based Multiple 2DEG Channel BRIDGE (Buried Dual Gate) HEMT Technology for High Power and Linearity

277 EDL High Breakdown Voltage in RF AlN/GaN/AlN Quantum Well HEMTs

275 APL Wurtzite phonons and the mobility of a GaN/AlN 2D hole gas

271 JAP Polarization control in nitride quantum well light emitters enabled by bottom tunnel-junctions

268 JJAP The new nitrides: layered, ferroelectric, magnetic, metallic and superconducting nitrides to boost the GaN photonics and electronics eco-system

266 Phys. Rev. Applied Broken symmetry effects due to polarization on resonant tunneling transport in double-barrier nitride heterostructures

2018

261 EDL Gate-recessed E-mode p-channel HFET with high on-current based on GaN/AlN 2D hole gas

257 DRC Realization of the First GaN Based Tunnel Field-Effect Transistor

250 APL Room temperature microwave oscillations in GaN/AlN resonant tunneling diodes with peak current densities up to 220 kA/cm2

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

243 CLEO Tunnel-junction p-contact sub-250 nm deep-UV LEDs

239 DRC High-temperature p-type polarization doped AlGaN cladding for sub-250 nm deep-UV quantum well LEDs by MBE

234 Phys. Rev. X New Tunneling Features in Polar III-Nitride Resonant Tunneling Diodes

229 APL Electron mobility in polarization-doped Al0-0.2GaN with a low concentration near 1017 /cm3

224 APL Strained GaN Quantum-Well FETs on Single-Crystal Bulk AlN Substrates

2015

202 DRC Deep-UV LEDs using polarization-induced doping: Electroluminescence at cryogenic temperatures

201 DRC High-voltage polarization-induced vertical heterostructure p-n junction diodes on bulk GaN substrates

199 IEDM Steep subthreshold swing tunnel FETs: GaN/InN/GaN and transition metal dichalcogenide channels

197 APL Ferroelectric transition in compressively strained SrTiO3 thin films

196 APL Polarization-induced Zener tunnel diodes in GaN/InGaN/GaN heterojunctions

192 JXCDS Transistor Switches using Active Piezoelectric Gate Barriers

191 JXCDS Polarization-Engineered III-Nitride Heterojunction Tunnel Field-Effect Transistors

2014

180 IEDM Sub 60mV/decade Steep Transistors with Compliant Piezoelectric Gate Barriers

176 DRC GaN lateral PolarSJs: Polarization-doped super junctions

163 EDL GaN Heterostructure Barrier Diodes (HBD) exploiting Polarization-induced Delta-doping

162 APL Two-dimensional electron gases in strained quantum wells for AlN/GaN/AlN double heterostructures FETs on AlN

158 APL Tunnel-Injection Quantum Dot deep-UV LEDs with Polarization-Induced Doping in III-Nitride Heterostructures

2013

148 EDL Polarization-Induced GaN-on-Insulator E/D Mode p-Channel Heterostructure FETs

133 APL Tunnel-injection GaN quantum-dot ultraviolet light-emitting diodes

2012

126 DRC A surface-potential based compact model for GaN HEMTs incorporating polarization charges

124 DRC Ultra-thin Body GaN-on-insulator nFETs and pFETs: Towards III-nitride complementary logic

122 APL Polarization effects on gate leakage in InAlN/AlN/GaN HEMTs

117 JAP Surface potential analysis of AlN/GaN heterostructures by electrochemical capacitance-voltage measurements

108 EDL Effect of Optical Phonon Scattering on the Performance of GaN Transistors

107 EDL Ultra thin GaN-on-Insulator Quantum Well FETs with Regrown MBE Contacts Â

102 Semic. Sc. Tech. Charge transport in non-polar and semi-polar III-V nitride heterostructures

2011

93 APL Presence and origin of interface charges at atomic-layer deposited Al2O3/III-nitride heterojunctions

92 APL N-Polar III-nitride quantum well light emitting diodes with polarization-induced doping

85 APL Stark-Effect Scattering in Rough Quantum Wells

81 Phys. Stat. Sol. Subcritical Barrier AlN/GaN E/D-Mode HFETs and Inverters

79 Phys. Stat. Sol. Polarization Engineering in Group-III Nitride Heterostructures: New Opportunities for Device Design

2010

74 APL High mobility two-dimensional electron gases in nitride heterostructures with high Al composition AlGaN alloy barriers

69 APL Polarization-mediated remote surface roughness scattering in ultrathin barrier GaN high-electron mobility transistors

68 Phys. Rev. B Anisotropic charge transport in nonpolar GaN quantum wells: Polarization-induced line charge and interface roughness scattering

67 EDL Gate-recessed Enhancement-Mode InAlN/AlN/GaN HEMTs with 1.9 A/mm Drain Current Density and 800 mS/mm Transconductance

65 EDL Threshold Voltage Control in Al0.72Ga0.28N/AlN/GaN HEMTs by Work-Function Engineering

64 Phys. Stat. Sol. Short-period AlN/GaN p-type superlattices: Hole transport usage in p-n Junctions

61 APL Polarization-engineered removal of buffer leakage for GaN Transistors

60 Science Polarization Induced Hole Doping in Wide Bandgap Uniaxial Semiconductor Heterostructures

2009

59 Phys. Rev. Lett. Polarization Induced Zener Tunnel Junctions in Wide Bandgap Heterostructures

2008

47 DRC Polarization Induced Graded AlGaN p‐n Junction grown by MBE

36 APL Very Low Sheet Resistance and Shubnikov de-Haas Oscillations in Two-Dimensional Electron Gases at Ultrathin Binary AlN/GaN Heterojunctions

2007

30 ECS Trans. MBE-grown Ultra-Shallow AlN/GaN HFET Technology

26 APL A High-Mobility Window for Two-Dimensional Electron Gases at Ultrathin AlN/GaN Heterojunctions

23 Phys. Rev. Lett. Enhancement of carrier mobility in semiconductor nanostructures by dielectric engineering

2006

22 JAP Compositional modulation and optical emission in AlGaN epitaxial films

17 APL Carrier transport and confinement in polarization-induced 3-D electron slabs: Importance of alloy scattering

16 APL Electron mobility in graded AlGaN alloys

2004

13 JAP Dipole Scattering in highly polar semiconductor alloys

12 APL AlGaN/GaN polarization-doped field-effect transistor for microwave power applications

2003

11 Phys. Rev. B Magnetotransport properties of a polarization-doped three-dimensional electron slab

9 Phys. Stat. Sol. Magnetotransport measurement of effective mass, quantum scattering time, and alloy scattering potential of polarization-doped 3D electron slabs

2002

6 APL Realization of wide electron slabs by polarization bulk doping in graded III-V nitride semiconductor alloys