On charge transport and low-frequency noise in the GaN p-i-n diode

The current-voltage (I-V) characteristics and low-frequency noise of the GaN p-i-n diodes were investigated in temperature range from 10 K to 300 K. We found that the reverse biased p-i-n diode made of GaN/AlGaN exhibits features of the space charge limited (SCL) current flow and its I-V characteristics can be approximated by the power law I similar to V-n relation. This phenomenon can be attributed to the presence of the multiple charge traps in the intrinsic region of device. It has been demonstrated that the direct tunneling from traps to bands may occur in diodes at forward and reverse bias with strong support of the Frenkel effect. The low frequency noise in our devices does not depend on temperature in both bias directions under cryogenic conditions. The observed low-frequency noise features support the hypothesis that excess tunneling current and recombination at grain boundaries are origins of the 1/f low-frequency noise in the diode at forward bias. The 1/f noise in the reverse bias regime can be described as a composition of many Lorentzian noise components that originate from traps, which have specific depth distribution.