Controllable physicochemical properties of WO thin films grown under glancing angle

In this work, various physicochemical properties are investigated in nanostructured WO thin films prepared by radio-frequency magnetron sputtering for optoelectronic applications. A glancing angle of 87° is employed to grow films of different thicknesses, which are then exposed to post-growth annealing. Detailed local probe analyses in terms of morphology and work function of WO films are carried out to investigate thickness-dependent property modulations of the as-deposited and annealed films. The analyses show a reasonably good correlation with photoelectron spectroscopic measurements on the films and the bulk I-V characteristics acquired on a series of WO/p-Si heterojunction diodes. The presence of a critical WO thickness is identified to regulate the rectification ratio values at the WO/p-Si heterostructures and increase in series resistance within the bulk of the films. The present study provides valuable insights to correlate optical, electrical, and structural properties of WO thin films, which will be beneficial for fabricating WO-based optoelectronic devices, including photovoltaic cells.