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

Abstract

We have demonstrated high-performance InAlN/ GaN MOS high-electron-mobility-transistors (MOSHEMTs) with various channel lengths ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{\mathrm {{ch}}}$ </tex-math></inline-formula> ) of 85–250 nm using atomic-layer-epitaxy (ALE) crystalline Mg <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.25</sub> Ca <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.75</sub> 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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3\times 10^{-13}$ </tex-math></inline-formula> A/mm, ON/OFF ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 10^{12}$ </tex-math></inline-formula> , almost ideal subthreshold swing of 62 mV/decade, low drain current noise with Hooge parameter of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-4}$ </tex-math></inline-formula> , and negligible current collapse and hysteresis are realized. The 85-nm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_{\mathrm {ch}}$ </tex-math></inline-formula> MOSHEMT also exhibits good ON-state performance with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I_{d\mathrm {max}}=2.25$ </tex-math></inline-formula> A/mm, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm{\scriptscriptstyle ON}}=1.3~\Omega \cdot \textrm {mm}$ </tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{\mathrm {max}}=475$ </tex-math></inline-formula> mS/mm, showing that ALE MgCaO is a promising gate dielectric for GaN device applications.