No significant contribution of hole-trap-enhanced conductivity modulation in GaN p+n diodes formed on low-dislocation-density GaN substrates

Abstract

Influences of hole traps on large forward current (I F) of GaN p+n diodes on low-dislocation-density (≤4 × 105 cm−2) GaN substrates were numerically investigated. As with the reported simulation of GaAs p+n diodes, hole traps were found to increase the electron concentration in the drift layer when forward voltage V F was increased. To reproduce the measured I F/V F characteristics, however, we had to assume an unrealistic electron mobility increasing with the electric field. We, therefore, concluded that sources other than hole traps were responsible for the reported enhancement of conductivity modulation in GaN p+n diodes.