Optimisation of Negative Fixed Charge Based Edge Termination for Vertical GaN Schottky Devices

Area of Science:

• Materials Science
• Semiconductor Physics
• Electrical Engineering

Background:

• Vertical Gallium Nitride (GaN) Schottky diodes are crucial for power electronics.
• Enhancing breakdown voltage (BV) is key to improving device performance and reliability.
• Edge termination techniques are vital for preventing premature device failure.

Purpose of the Study:

• To investigate the impact of negative fixed charge, introduced by fluorine (F) implantation, on BV enhancement in vertical GaN Schottky diodes.
• To determine the optimal negative fixed charge concentration for maximizing BV using TCAD simulations.
• To propose an empirical equation for predicting the optimum fixed charge concentration based on depth.

Main Methods:

• Utilizing Synopsys Sentaurus TCAD for device simulations.
• Modeling a vertical GaN Schottky diode with a negative fixed charge region for edge termination.
• Analyzing device and implant-related parameters, including fluorine implantation profiles from SIMS data.

Main Results:

• Demonstrated that negative fixed charge via fluorine implantation significantly impacts BV.
• Identified an optimal range for negative fixed charge concentration for highest BV.
• Showcased similar BV dependence on key parameters for both box and realistic implantation profiles.

Conclusions:

• Negative fixed charge is an effective strategy for enhancing BV in vertical GaN Schottky diodes.
• The study provides a method for optimizing edge termination using fluorine implantation.
• Findings offer valuable insights for the design of high-performance GaN power devices.