ZnO nanorod based highly selective visible blind ultra-violet photodetector and highly sensitive NO2 gas sensor

By using 1D ZnO nanorod, obtained from a simple two step chemical method as the sensor material, we report the fabrication of highly selective metal-semiconductor-metal (MSM) ultraviolet (UV) photodetector and NO2 gas sensor. The fabricated MSM UV photodetector and gas sensor possesses simplicity in material synthesis and sensor design. The effect of morphological evolution and structural intactness on the sensing properties of UV photodetector and NO2 gas sensor are deeply studied. The well aligned 1 dimensional (1D) ZnO nanorod provides high surface area for the sensing mechanism. The UV photodetector possesses high responsivity in the UV A region (364.81 A/W) with fast photoswitching characteristics at 5 V bias. It shows formation of good ohmic contact between metal semiconductor junctions. NO2 sensing measurement was carried out at relatively lower temperature of about 175 degrees C. The ZnO nanorods are highly selectivity towards NO2 gas and maximum gas response observed is 35 at 40 ppm of NO2. The NO2 gas sensor shows good repeatability at lower gas concentration of 2 ppm. The present synthesis technique provides cost effective route for obtaining highly ordered ZnO nanorods with simple sensor technology for multifunctional ZnO nanorod sensor.