Controllable physicochemical properties of WO _x thin films grown under glancing angle

In this work, various physicochemical properties are investigated in nanostructured WO _x 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 _x 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 _x /p-Si heterojunction diodes. The presence of a critical WO _x thickness is identified to regulate the rectification ratio values at the WO _x /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 _x thin films, which will be beneficial for fabricating WO _x -based optoelectronic devices, including photovoltaic cells.