Field-induced Acceptor Ionization in Enhancement-mode GaN p-MOSFETs
Nadim Chowdhury, Qingyun Xie, John Niroula, Nitul S. Rajput, Kai Cheng, Han Wui Then, Tomás Palacios
Abstract
This work demonstrates a p-MOSFET with a GaNM.l <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.2</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.8</sub> N (20 nm)/GaN heterostructure grown by metal-organic-chemical vapor deposition (MOCVD) on 6-inch Si substrate with optimized self-aligned process. Devices with source-to-drain distance, L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SD</sub> , varying from 1 μm down to 200 nm were fabricated. Significant field-induced acceptor ionization was found in these devices at high drain voltages. The device with L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SD</sub> =200 nm shows a record combination of I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> of ~45 mA/mm and ON-OFF ratio of ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> when compared with other p-channel transistor demonstrations. The device also exhibits Enhancement-mode operation with threshold voltage of -0.5V. The best device shows an ON-current of 100 mA/mm but at the expense of lower on-off ratio of ~10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .