Oxygen Induced Enhanced Photoanodic Response of ZnTe:O Thin Films: Modifications in Optical and Electronic Properties
2017
Sharma, Intu | Singh, Aadesh P. | Tyagi, Neha | Saini, Nishant | Auluck, Sushil | Mehta, Bodh R.
In the present work, photoanodic response of ZnTe thin films is enhanced by incorporating oxygen, which is explained by analyzing oxygen-induced modifications in structural, optical, and electronic behavior of ZnTe thin films, using detailed experimental characterizations and density functional theory (DFT) based calculations. On incorporating oxygen, the nanocrystalline character of ZnTe is increased with a change in optical properties due to absorption through sub band states and an increase in fundamental absorption edge. From DFT analysis, origin of these sub band gap states is attributed to oxygen incorporation induced electronic states and Te vacancies. Photoelectrochemical (PEC) performances of ZnTe with and without oxygen have been investigated where a change over from photocathodic response for ZnTe to enhanced photoanodic response for ZnTe:O thin films along with increased response for low energy photons is observed. These findings are explained in terms of oxygen induced modification in visible light absorption, enhanced surface area due to increased nanocrystalline character and modified electronic properties of ZnTe:O thin films. Modifications in optical properties and enhancement in PEC performance by oxygen incorporation shown in the present study may be useful for developing ZnTe-based photovoltaic devices.
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