A Study of Reverse Characteristics of GaN-on-Si Quasi-Vertical PiN Diode with Beveled Sidewall and Fluorine Plasma Treatment

In this work, we show a high-performance GaN-on-Si quasi-vertical PiN diode based on the combination of beveled sidewall and fluorine plasma treatment (BSFP) by an inductively coupled plasma (ICP) system. The leakage current and breakdown voltage of the diode are systematically studied. Due to the beveled sidewall treated by the fluorine plasma, the diodes achieve an excellent breakdown voltage (V_BR) of 790 V and a low reverse leakage current. In addition, the GaN-on-Si quasi-vertical PiN diode achieves a low specific on-resistance (R_on,sp) of 0.51 mΩ·cm² and a high Baliga's figure of merit (BFOM) of 1.22 GW/cm². The relationship between the total leakage current and the device diameter shows that the sidewall leakage is the main leakage path of the device. Afterwards, the TCAD simulations based on electric field and electric potential reveal that the fluorine plasma treatment is a major factor in suppressing the leakage current and increasing the V_BR for a diode with BSFP. This work systematically analyzes the effects of beveled sidewall and fluorine plasma treatment based on the reverse characteristics of the GaN-on-Si quasi-vertical PiN diode and highlights the great potential of the GaN-on-Si PiN diode for various power applications.