Preparation and Characterization of P-type semiconductor transparent oxide thin Films

Abstract

Transparent conducting oxide (TCO) have been extensively used in scientific and technological applications. Currently, n-type TCOs are present in many electronic devices, while their p-type counterparts are not largely commercially available and have limitations in stability and material synthesis. Nickel oxide (NiO) is a promising candidate as a p-type transparent conducting oxide film due to superior characteristics, such as high chemical stability, good crystallinity, wide direct energy gap in the range of 3.5 – 4.0 eV and low material cost. The preparation of controlled quality NiO films at low deposition temperature is challenging task because their properties depend on the film stoichiometry. In the present work, NiO films were deposited by chemical bath deposition (CBD) and chemical spray pyrolysis (CSP) methods which allow improving the quality of the deposited films by changing of deposition parameters. XRD analysis proved that the as-deposited films by CBD are nickel hydroxide phase which transformed to poly-crystalline NiO phase by annealing process at 450°C in air for 4 hours. SEM images showed that the NiO films have a nanoflakes structure which makes these films fitting for gas sensing application. In addition, NiO films have been deposited by CSP using different precursor solution as well as different deposition temperature. The XRD prove the sprayed NiO films are polycrystalline and have a cubic crystal structure with (111) preferred orientation. The SEM images showed that the surface morphology of sprayed NiO films was changed by using different precursor solution. XPS results confirmed that the changes of initial nucleation, chemical composition and structure of NiO films depend on the Ni/O