Vertical GaN Junction Barrier Schottky Rectifiers by Selective Ion Implantation

Abstract

This letter demonstrates vertical GaN junction barrier Schottky (JBS) rectifiers fabricated with novel ion implantation techniques. We used two different methods to form the lateral p-n grids below the Schottky contact: 1) Mg implantation into n-GaN to form p-wells and 2) Si implantation into p-GaN to form n-wells. Specific differential ON-resistances ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> ) of 1.5–2.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega ~\cdot $ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and 7–9 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\Omega ~\cdot $ </tex-math></inline-formula> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> were obtained in the Mg-implanted and Si-implanted JBS rectifiers, respectively. A breakdown voltage of 500–600 V was achieved in both devices, with a leakage current at high reverse biases at least 100-fold lower than conventional vertical GaN Schottky barrier diodes. The impact of n-well and p-well widths on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{ \mathrm{\scriptscriptstyle ON}}$ </tex-math></inline-formula> and BV was investigated. Fast switching capability was also demonstrated. This letter shows the feasibility of forming patterned p-n junctions by novel ion implantation techniques, to enable high-performance vertical GaN power devices.