β-Ga₂O₃ Lateral High-Permittivity Dielectric Superjunction Schottky Barrier Diode With 1.34 GW/cm² Power Figure of Merit

Abstract

In this work, we demonstrate lateral <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\beta }$ </tex-math></inline-formula> -Ga2O3 Schottky barrier diode (SBD) with a high permittivity (high-k) dielectric superjunction (SJ) structure. Trenches are patterned on the doped <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\beta }$ </tex-math></inline-formula> -Ga2O3 epilayer from anode to cathode and high permittivity BaTiO3 dielectric is deposited on the trenches to uniformly distribute the electric field in the epilayer, which circumvents the extreme difficulties in achieving charge balance using conventional p-n superjunction structures in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\beta }$ </tex-math></inline-formula> -Ga2O3 due to the lack of shallow acceptors. The proposed structure also enables the use of heavily doped epilayer to reduce on-resistance and also can achieve high breakdown voltage due to charge balance effect arising out of dielectric polarization. SBD on an epilayer with a sheet charge of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${1.5}\times {10}^{{13}}$ </tex-math></inline-formula> cm−2 demonstrates a specific on resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{R}_{\text {on-sp}}$ </tex-math></inline-formula> ) of 1.65 m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\Omega }$ </tex-math></inline-formula> -cm2 and a breakdown voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\text {BR}}$ </tex-math></inline-formula> ) of 1487 V for an anode to cathode length of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5 ~{\mu }\text{m}$ </tex-math></inline-formula> rendering a Power figure of Merit (PFOM) of 1.34 GW/cm2 when normalized to the entire device footprint. Normalizing to the active current conducting area yields a PFOM of 2.7 GW/cm2 which crosses the SiC unipolar PFOM. These results using the proposed device structure demonstrates great promise for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\boldsymbol {\beta }$ </tex-math></inline-formula> -Ga2O3 in multi-kilovolt class applications.