Effects of p-GaN Body Doping Concentration on the ON-State Performance of Vertical GaN Trench MOSFETs
Renqiang Zhu, Huaxing Jiang, Chak Wah Tang, Kei May Lau
Abstract
In this letter, we report the influence of p-GaN body doping concentration on the ON-state performance of vertical GaN trench MOSFETs. Decreasing the p-GaN body doping concentration leads to an enhanced maximum drain current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D,max</sub> ), reduced specific ON-resistance (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON,sp</sub> ), but also a decreased threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ), suggesting that the p-GaN doping plays an important role in balancing the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> , R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON,sp</sub> and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D,max</sub> in vertical GaN trench MOSFETs. Resulting from the tuning of Mg concentration in the p-GaN, we demonstrate high ON-performance including a high I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D,max</sub> of 2.8 kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a low R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON,sp</sub> of 0.87 mΩ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a large V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> of 4.8 V in a quasi-vertical GaN trench MOSFET on sapphire with a 2.5- μm-thick drift layer, while maintaining a breakdown voltage of 273 V.