High Rectification, Low Leakage p-Si/n-AlN Heterojunction PN Diode

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 $1100~^{\circ }$ C with contact resistivity of ${4}.{9}\times {10}^{-{3}}~\Omega \cdot $ cm2. The PNDs exhibited remarkable uniformity across the wafer, excellent rectifying characteristics with a high ratio of $\sim {3}\times {10}^{{7}}$ at ±10 V, low leakage current density of $\sim {6}.{25}\times {10}^{-{9}}$ A/cm2 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~\Omega \cdot $ cm2 as temperature increased from room temperature to $100~^{\circ }$ 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.