Low Turn-On Voltage and High Breakdown Voltage β-Ga₂O₃ Diode With Fin Channel and Ohmic Contact Anode

Abstract

In this work, a low turn-on voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{ \mathrm{\scriptscriptstyle ON}}}$ </tex-math></inline-formula> ) and high breakdown voltage (BV) beta-phase gallium oxide ( <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) diode with a Fin channel combined with an ohmic contact anode and composite field-plate (FOCF) is proposed. Its electrical characteristics are investigated by Sentaurus TCAD simulation. The novel FOCF diode has two features: one is a Fin channel combined with ohmic contact anode (FO) to achieve metal–insulator–semiconductor (MIS)-like forward/reverse characteristics and thus realize a very low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{ \mathrm{\scriptscriptstyle ON}}}$ </tex-math></inline-formula> ; the other is composite field-plate (CF) to improve BV, consisting of Al2O3 and SiN <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{X}$ </tex-math></inline-formula> dual-dielectric layers to form step-shaped field plate. When the forward voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{\text {F}}}$ </tex-math></inline-formula> ) is 0 V, the Fin channel is pinched off due to the work function difference between the anode metal and <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; thus, the pinch-off effect allows the ohmic contact anode to take place of Schottky contact anode to significantly reduce <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{ \mathrm{\scriptscriptstyle ON}}}$ </tex-math></inline-formula> . As <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{\text {F}}}$ </tex-math></inline-formula> increases, the electron accumulation layers can be formed along the Fin sidewalls to improve current capability and reduce ON-resistance. Moreover, the pinch-off effect suppresses reverse leakage current and CF modulates the electric field distribution, both of which improve BV. The proposed FOCF <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 diode achieves low <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{{ \mathrm{\scriptscriptstyle ON}}} =0.45$ </tex-math></inline-formula> V, high BV <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$=$ </tex-math></inline-formula> 2204 V, and Baliga’s figure of merit (BFOM) up to 1.47 GW/cm2. Therefore, the proposed structure provides a new design concept and enhances the application potential for high-power and low-loss <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 diodes.