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

Rupam Mandal; Aparajita Mandal; Alapan Dutta; Rengasamy Sivakumar; Sanjeev Kumar Srivastava; Tapobrata Som

doi:10.3762/bjnano.15.31

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

Beilstein J Nanotechnol. 2024 Apr 2:15:350-359. doi: 10.3762/bjnano.15.31. eCollection 2024.

Authors

Rupam Mandal^#^{1

2}, Aparajita Mandal^#¹, Alapan Dutta^{1

2}, Rengasamy Sivakumar³, Sanjeev Kumar Srivastava⁴, Tapobrata Som^{1

2}

Affiliations

¹ SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha, India.
² Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai 400 094, India.
³ Department of Physics, Alagappa University, Karaikudi 630 003, India.
⁴ Department of Physics, Indian Institute of Technology Kharagpur, Kharagpur 721 302, India.

^# Contributed equally.

Abstract

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.

Keywords: annealing; glancing angle sputter deposition; heterojunction; tungsten oxide; work function.