Numerical study and design of high-efficiency p-In0.1Ga0.9N/i-GaN/n-GaN heterojunction photodiode

This paper reports the performance of a proposed GaN heterojunction p-i-n photodiode with a ptype In0.1Ga0.9N layer. The simulation results show that, compared with the GaN homojunction pi-n structure, the GaN heterojunction p-i-n structure performs better on the basis of such simulations as photocurrent density and responsivity. The effects of reverse bias voltage, light intensity and i-GaN absorbing layer thickness are explored. The peak responsivity and the cutoff frequency are found to increase remarkably with increasing reverse bias voltage. The degradation of device responsivity and cutoff frequency at high optical excitation power density are also investigated. By increasing the i-GaN absorbing layer thickness, responsivity increases but cutoff frequency decreases. The maximum responsivity is 0.3 A/W at 0.363 mu m under an illumination intensity of 105 W/cm2 and an applied reverse bias voltage of -2 V, while the highest cutoff frequency 12 GHz is achieved at an applied reverse bias voltage of -14 V.