Production and characterization of nanorod-based photodi̇odes

In this thesis, we have investigated the effects of ZnO thin films prepared in different molar solution (1 ml and 5 ml) and annealing time exposure (3h, 5h and 7h) on the crystallization quality, microstructure analysis and basic electric and electronic properties of Au/ZnO NR/ZnO(100 nm)/n-GaAs/Au metal–semiconductor structures from the parents of Hetero Junction Structure (HJS) using the current-voltage (I–V) characteristics measurements performing at the forward and reverse regions for the first time. All the tests have experimentally been conducted in case of 3V operating voltage at the constant temperature of 295 K (room temperature). The raw data of I–V experimental curves have enabled us to determine some fundamental electronics quantitates including the series resistance (Rs), shunt resistance (Rsh), ideality factor (n), and barrier height (ΦB0) parameters with the aid of thermionic emission, Cheung and Cheung's function and modified Norde's function approaches based on the developed LabVIEW software program so that we can easily discuss whether the produced HJS devices are economically proper for the potential application areas such as the sensors, memory elements and rectifying devices or not. Firstly, the crystallinity qualities for the ZnO nanorods produced under different environmental conditions are sensitively examined by means of the powder X-ray diffraction (XRD) method. It is found that the ZnO material exposed to the 5 molar solution and main heat treatment for 3 hours possesses the best crystal quality, crystallization and orientation of the grains. Secondly, the scanning electron microscopy (SEM) studies performed for microstructure analyzes show that all the materials produced in this work exhibit the high crystalline quality within the certain orientation of grains. Similarly, the sample produced at solution molarity of 5 ml and heat treatment time of 5 h has the maximum average layer thickness of 1650 nm for the nanorods produced. According to the results obtained, it is normal to confirm that the applied heat treatment leads to a positive effect on the layer thickness of the ZnO nanorods. Thirdly, the experimental and theoretical findings related to basic electric and electronic features display that the fundamental quantities of n, ΦB0, RR tend to enhance dramatically with the decrement in the ZnO thicknesses founded on molar and time exposure. Similarly, the parameter of Rsh values have been noted to increase significantly with the augmentation in the time exposure. In fact, the Rsh value have reached their maximum point as the combination of molar and time exposure have been x=35.0 and t=3 h, respectively. On the other hand, the Rs parameters have been found to be almost close values to each other. Based on the experimental evidences and theoretical computations, it can be claimed that 5 molar and 3 h exposure time are the best preparation conditions for the ZnO thin film layered HJS materials to be used in the advanced sensor applications.