Self-Powered GaN-Based MSM Ultraviolet Photodetector With Asymmetrical Interdigitated Structure

In this work, we propose a self-powered GaN-based high-performance metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector (PD) with an asymmet-rical interdigitated structure. Benefiting from the device's asymmetrically distributed energy band characteristics between the two electrodes, the peak responsivity (R) of 0.024 A/W under UV illumination corresponding to a high detectivity (D*) of 6.6 x 1012 cmW-1 Hz(1/2) (Jones) can be obtained when the device is biased at 0 V. The results show that the self-powered function of the device can be achieved by using an asymmetric interdigitated structure. We illustrate the origin of the fabricated device's pho-toresponse in the absence of bias with the assistance of energy band structure analysis, which can be attributed to the energy band bending caused by the polarization effect in AlGaN/GaN heterojunction. In addition, a high peak responsivity of 115 A/W and a photocurrent (I-photo) of 2.66 x 10(-5) A at an applied bias voltage of 10 V was achieved. A dark current (I-dark) of 1.18 x 10(-10) A was also measured, giving the device a photocurrent-dark current ratio (I-photo/I-dark) of 105. In short, the results show that the proposed self-powered GaN-based UV PD has the potential for high-sensitivity UV detection.