MSM Blue-Light Photodetector with Unilateral Recessed Electrode Structure
To improve the performance of InGaN-based visible light detectors,a unilateral recessed interdigital electrode MSM-type blue light photodiode based on a GaN/InGaN MQWs epitaxial material is fabricated and measured.The I-V characteristic measurement results of the device show that,compared with traditional planar electrode devices,recessed electrode devices have smaller and flatter dark currents and larger photocurrents with increasing bias.Spectral response measurements show that the cutoff band edge of the device is located near 490 nm,and the rejection ratio at the band edge of the recessed electrode device is one order of magnitude higher than that of the planar electrode device.At a bias voltage of 5 V,the responsivity of the recessed electrode device is 0.034 6 A/W@480 nm,corresponding to an external quantum efficiency of 8.94％,that is higher than that of the planar electrode device.The improvement in device performance is attributed to the effective suppression of the surface conduction leakage current and the improved distribution of the built-in electric field achieved by the unilateral recessed electrode structure.This results in a reduced dark current in the device and enhances the collection of photogenerated carriers by the electrodes,thereby increasing the responsivity.
blue light detectorMSMGaN/InGaN MQWsunilateral recessed electrodesbuilt-in electric field distribution
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