Transient current analysis of a GaN radiation detector by TCAD

• A TCAD model is established for a GaN Schottky diode radiation detector.
• Schottky side mainly collects holes, while ohmic side solely collects electrons.
• The funneling region evolution is visualized by carrier current densities.
• Carrier generation/loss by impact ionization/trapping is insignificant.
• The collected charges are primarily drift carriers in the depletion region.

A gallium nitride (GaN) Schottky diode radiation detector has been fabricated with a successfully demonstrated radiation response to alpha particles and neutrons when using Li as a convertor. In order to understand the charge collection process for further device modification, the Sentaurus TCAD software package is employed to quantitatively study the transient current produced by energetic charge particles. By comparing the simulation and experimental results, especially the capacitance–voltage relationship and charge collection efficiency, the device parameters and physics models used for the simulation are validated. The time behavior of the transient current is studied, and the carrier generation/loss by impact ionization, recombination, and trapping are discussed. The total collected charge contributed by various components, such as drift, funneling, and diffusion are also analyzed.