Optimization and Characterization of SILAR Synthesized ZnO Nanorods for UV Photodetector Sensor

Abstract In the current research, zinc oxide (ZnO) nanorods (NRs) have been grown upon glass-slide substrates by employing the effective chemical bath deposition (CBD) method at low-temperature. ZnO seed-layer has been coated over the whole substrates by using very simplicity successive ionic-layer adsorption and reaction (SILAR) approach. The impact of the four different SILAR process cycle for ZnO seed-layer deposition on the characteristic of ZnO NRs have been investigated. The surface morphological, structural, optical properties of the produced ZnO NRs have been studied using several techniques for different SILAR process cycles. Also, the high-quality UV photodetector (PDs) based on ZnO NRs at different SILAR process cycles have been successfully fabricated by applying bias voltage in range of (-5 V to 5 V). The results indicated that the variation of SILAR process cycles have the large and significant impact on the morphological, structural, and optical properties of ZnO NRs. The average size and length of fabricated ZnO NRs were increased with increases the SILAR cycles in the range of 32-98 nm and 291-1210 nm, respectively. The large aspect ratio was noted for ZnO NRs formed at 15 SILAR cycles about 14.93. The growth rate and crystal size of ZnO NRs were increases with increases the SILAR cycles in the range of 1.161-6.722 nm/min and 28.9-94.24 nm/min, respectively. All the samples display a dominant peak at wavenumber of 436.5 cm-1 which is attributed to the E2 active mode and characteristic of the hexagonal phase of ZnO NRs. The energy gap of ZnO NRs was decreased from 3.25 eV to 3.23 eV as the SILAR cycles increases from 5 cycles to 20 cycles. The overall ultraviolet (UV) emission peak centered at 380 nm is found to correlate to near-band emissions (NBE). The ZnO NRs based UV-detector displays repeatable characteristics with a peak photoresponse of 116.6 μA. The UV-sensor based ZnO NRs grown at 15 SILAR process cycles at 5 V bias voltage shows optimal performance responsivity, high photosensitivity, low dark current, quick rise and recovery times were 0.5477 A/W, 3573.57 %, 3.1743 μA, 1.04259 s, and 0.3046 s, respectively.