Highly sensitive and cost-effective metal-semiconductor-metal asymmetric type Schottky metallization based ultraviolet photodetecting sensors fabricated on n-type GaN

Cost effective and highly sensitive Cr/Ni/Cu/n-GaN/Ti/Al asymmetric type metal-semiconductor-metal (MSM) Schottky barrier ultraviolet photodetector has been fabricated at room temperature. Surface morphological and oxidation states of Cr and Ni metal layers were investigated using atomic force microscopy and X-ray absorption spectroscopy, respectively. Current-voltage (I–V) measurements were performed in dark and at various wavelength illuminations in the range 350–370 nm indicated a very good rectification ratio of 1.5–4.6 × 104 (at ± 7 V) due to the utilisation of two metal stacks with different workfunctions. The Schottky diode parameters such as Schottky barrier height, ideality factor and series resistance were calculated at different wavelength illuminations using different reliable approaches. The spectral responses measured from the fabricated GaN based UV PD at several biases in the wavelength range 300–450 nm were found to be bias dependent due to the internal gain effect. Using time dependent photoresponses the rise/fall time values were evaluated at 5 V of different wavelengths and were found to be in the range 1.55–2.05 s and 2.92–3.35 s, respectively. Consequently, from current-voltage (I–V), photoresponsivity and time-dependent photoresponse studies, the 365 nm was found to be the optimum and reflects the high wavelength selectivity for the fabricated GaN based A-type MSM UV PD under study. •Cost effective and highly sensitive Cr/Ni/Cu/n-GaN/Ti/Al asymmetric type MSM SB UV PDs have been fabricated and reported.•The I–V characteristics measured in dark and under illumination of UV-A light revealed superior performance.•The time-dependent photoresponses executed for a period of 450 s at 5 V indicated stability of the fabricated device.