Wafer-scale high sensitive UV photodetectors based on novel AlGaN/n-GaN/p-GaN heterostructure HEMT

Abstract

We report a novel high sensitive ultraviolet (UV) photodetector based on AlGaN/n-GaN/p-GaN heterostructure high electron mobility transistor (HEMT) on sapphire substrates and have prepared four types of devices with identical lengths but different widths of the effective region on one wafer. Since the existence of the built-in electric field within p-GaN and n-GaN, the two-dimensional electron gases (2DEGs) at the AlGaN/n-GaN interface is effectively depleted, leading to ultra-low dark current at pA level. Under UV LED irradiation with wavelength of 365 nm, the photodetectors demonstrate extremely high light on/off ratio (Ilight/Idark) of about 106 and high photoresponse speed with the rise time (τrise)/decay time (τdecay) of 1.53 ms/2.21 ms at Vds = -5 V under light power density of 236.97 mW/cm2. Furthermore, the R of the photodetector reaches 9.12 A/W, the EQE and D* are as high as 3100 % and 1.95 × 1013 Jones, respectively, indicating overall high performances of the device in terms of photoresponsivity, EQE, detectivity and robust stability. The proposed photodetectors with merits of p-GaN etchless compared with conventional E-mode p-GaN HEMT and wafer-scale mass production may pave the way for the application of UV communication, Internet of Things and medical treatment.