Numerical study of high-efficient and high-speed In0.1Ga0.9 N/GaN multiple quantum well photodiodes

This paper presents a numerical simulation study of p-i-n photodiodes based on In0.1Ga0.9 N/GaN multiple quantum wells (MQWs) of 2.5-nm-thick In0.1Ga0.9 N QWs and 12-nm-thick GaN barriers embedded into the intrinsic regions. The device performance is evaluated by investigating both the spectral and the frequency responses. The simulated 10-period In0.1Ga0.9 N/GaN MQW photodiode exhibits a peak responsivity of 0.25 A/W at 0.35 μm under a light power density of 0.1 W.cm−2 at -2 V reverse bias voltage and a cutoff frequency of 460 MHz. The effects of the number of quantum wells, reverse bias voltage and polarization on the spectral and frequency responses are then investigated. It is found that the maximum responsivity is 0.29 A/W at 0.35 μm and the cutoff frequency is 8.2 GHz for a 15-period In0.1Ga0.9 N/GaN MQW structure under a reverse bias of -10 V and a polarization scale factor of 0.25. Increasing the polarization scale factor degrades the responsivity performance due to the increased recombination of photocarriers. On the other hand, the cutoff frequency increases significantly with polarization and reaches a high value of 28 GHz for a polarization scale factor of 0.9 due to the increase of the polarization-induced field in the QWs.