Ionic liquid gating on atomic layer deposition passivated GaN: Ultra-high electron density induced high drain current and low contact resistance

Herein, we report on achieving ultra-high electron density (exceeding 1014 cm−2) in a GaN bulk material device by ionic liquid gating, through the application of atomic layer deposition (ALD) of Al2O3 to passivate the GaN surface. Output characteristics demonstrate a maximum drain current of 1.47 A/mm, the highest reported among all bulk GaN field-effect transistors, with an on/off ratio of 105 at room temperature. An ultra-high electron density exceeding 1014 cm−2 accumulated at the surface is confirmed via Hall-effect measurement and transfer length measurement. In addition to the ultra-high electron density, we also observe a reduction of the contact resistance due to the narrowing of the Schottky barrier width on the contacts. Taking advantage of the ALD surface passivation and ionic liquid gating technique, this work provides a route to study the field-effect and carrier transport properties of conventional semiconductors in unprecedented ultra-high charge density regions.

[1]  J. Nelson,et al.  Metallic state of low-mobility silicon at high carrier density induced by an ionic liquid , 2015, 1505.00656.

[2]  Yoshihiro Iwasa,et al.  Ambipolar insulator-to-metal transition in black phosphorus by ionic-liquid gating. , 2015, ACS nano.

[3]  Hiroshi M. Yamamoto,et al.  Light-induced superconductivity using a photoactive electric double layer , 2015, Science.

[4]  D. Costanzo,et al.  Electrostatically induced superconductivity at the surface of WS₂. , 2015, Nano letters.

[5]  S. Cheong,et al.  Gate-tunable phase transitions in thin flakes of 1T-TaS2. , 2014, Nature nanotechnology.

[6]  P. Ajayan,et al.  Switching mechanism in single-layer molybdenum disulfide transistors: an insight into current flow across Schottky barriers. , 2013, ACS nano.

[7]  S. Cristoloveanu,et al.  High-Performance GaN-Based Nanochannel FinFETs With/Without AlGaN/GaN Heterostructure , 2013, IEEE Transactions on Electron Devices.

[8]  D. Tománek,et al.  Improved carrier mobility in few-layer MoS2 field-effect transistors with ionic-liquid gating. , 2013, ACS nano.

[9]  A. Fujiwara,et al.  Electric double-layer capacitance between an ionic liquid and few-layer graphene , 2013, Scientific Reports.

[10]  Y. J. Zhang,et al.  Superconducting Dome in a Gate-Tuned Band Insulator , 2012, Science.

[11]  Hongtao Yuan,et al.  Discovery of superconductivity in KTaO₃ by electrostatic carrier doping. , 2011, Nature nanotechnology.

[12]  Hongtao Yuan,et al.  Liquid-gated interface superconductivity on an atomically flat film. , 2010, Nature materials.

[13]  Hideo Ohno,et al.  Electric double layer transistor with a (Ga,Mn)As channel , 2010 .

[14]  Hongtao Yuan,et al.  High‐Density Carrier Accumulation in ZnO Field‐Effect Transistors Gated by Electric Double Layers of Ionic Liquids , 2009 .

[15]  W. Schaff,et al.  Probing and modulating surface electron accumulation in InN by the electrolyte gated Hall effect , 2008 .

[16]  P. Ye,et al.  High-Performance Inversion-Type Enhancement-Mode InGaAs MOSFET With Maximum Drain Current Exceeding 1 A/mm , 2008, IEEE Electron Device Letters.

[17]  Robert M. Wallace,et al.  GaAs interfacial self-cleaning by atomic layer deposition , 2008 .

[18]  S. Yoshida,et al.  Normally Off n-Channel GaN MOSFETs on Si Substrates Using an SAG Technique and Ion Implantation , 2007, IEEE Electron Device Letters.

[19]  P. Ye,et al.  GaN metal-oxide-semiconductor field-effect-transistor with atomic layer deposited Al2O3 as gate dielectric , 2006 .

[20]  K. Kim,et al.  Low-resistance Ohmic contacts for high-power GaN field-effect transistors obtained by selective area growth using plasma-assisted molecular beam epitaxy , 2006 .

[21]  Peide D. Ye,et al.  GaAs metal–oxide–semiconductor field-effect transistor with nanometer-thin dielectric grown by atomic layer deposition , 2003 .

[22]  Yuan Taur,et al.  Device scaling limits of Si MOSFETs and their application dependencies , 2001, Proc. IEEE.

[23]  A. Chin,et al.  High-Performance GaN MOSFET With High-$\kappa$ $\hbox{LaAlO}_{3}/\hbox{SiO}_{2}$ Gate Dielectric , 2012, IEEE Electron Device Letters.