High-Performance InAlN/GaN MOSHEMTs Enabled by Atomic Layer Epitaxy MgCaO as Gate Dielectric

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Abstract
We have demonstrated high-performance InAlN/ GaN MOS high-electron-mobility-transistors (MOSHEMTs) with various channel lengths ( $L_{\mathrm {{ch}}}$ ) of 85–250 nm using atomic-layer-epitaxy (ALE) crystalline Mg 0.25 Ca 0.75 O as gate dielectric. With a nearly lattice matched epitaxial oxide, the interface between oxide and barrier is improved. The gate leakage current of MOSHEMT is reduced by six orders of magnitude compared with HEMT. An OFF-state leakage current of $3\times 10^{-13}$ A/mm, ON/OFF ratio of $4\times 10^{12}$ , almost ideal subthreshold swing of 62 mV/decade, low drain current noise with Hooge parameter of $10^{-4}$ , and negligible current collapse and hysteresis are realized. The 85-nm $L_{\mathrm {ch}}$ MOSHEMT also exhibits good ON-state performance with $I_{d\mathrm {max}}=2.25$ A/mm, $R_{\mathrm{\scriptscriptstyle ON}}=1.3~\Omega \cdot \textrm {mm}$ , and $g_{\mathrm {max}}=475$ mS/mm, showing that ALE MgCaO is a promising gate dielectric for GaN device applications.
Funding Information
  • Air Force Office of Scientific Research monitored by Dr. K. Goretta (FA9550-12-1-0180)
  • Office of Naval Research (ONR) through the DEFINE Program (N00014-10-1-0937)
  • ONR within the NEPTUNE Program
  • National Renewable Energy Laboratory, Center for the Next Generation of Materials by Design, Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science (DE-AC36-08GO28308)

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