Our paper has been published in JAP2021!

Our paper describing the impact ionization coefficients and critical electric field in GaN has been published in J. Appl. Phys. 129, 185702 (2021). In this paper, We proposed a novel measurement method of avalanche multiplication factors utilizing the unique optical absorption induced by high electric field (the Franz-Keldysh effect). Based on the careful analysis of the device properties, the photocurrents and the avalanche multiplication factors, we successfully extracted the electron and hole impact ionization coefficients in GaN at 223-373 K. The impact ionization coefficients in GaN were formulated based on the Okuto-Crowell model, and the parameters were presented. The ideal avalanche breakdown voltage and critical electric field were simulated for GaN p-n junction with varied epitaxial structure, and were discussed in detail. We believe that this paper will be essential to consider impact ionization and its avalanche phenomena in GaN as well as a practical application for a device simulation of GaN power devices!