High Rectification, Low Leakage p-Si/n-AlN Heterojunction PN Diode
Yi Lu, Jie Zhou, Jiarui Gong, Yang Liu, Haicheng Cao, Mingtao Nong, Zhiyuan Liu, Md Tahmidul Alam, Chirag Gupta, Xiaohang Li, Zhenqiang Ma
Abstract
Ultrawide bandgap AlN is a highly attractive material for power and radio frequency electronics. Unipolar n-AlN Schottky barrier diodes have demonstrated their strengths, whereas further development of AlN-based bipolar devices is desired but lacked. In this letter, we report single-crystalline p-Si/n-AlN p-n diodes (PNDs) with superior performance, accomplished by grafting a p-type Si nanomembrane onto an n-AlN film. Improved Ohmic contact directly on n-AlN was obtained through high temperature annealing at 1100 °C with contact resistivity of 4.9×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> Ω cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>. The PNDs exhibited remarkable uniformity across the wafer, excellent rectifying characteristics with a high ratio of ~3×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> at ±10 V, low leakage current density of ~6.25×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> A/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at -10 V, and hysteresis-free operation from -10 V to 30 V. Furthermore, the devices demonstrated superior thermal stability, with the on-resistance decreasing from 15.8 to 0.33 Ωcm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> as temperature increased from room temperature to 100 °C, revealing an activation energy of ~425 meV for deep donor state in AlN. No destructive breakdown of the devices was observed up to –894 V. These results highlight the Si/AlN PNDs’ potential for development of AlN-based electronic devices.