Importance of strain reduction in improvement of optical transmission and conductance in Si4+ doped ZnO: a probable new moisture resistant Transparent Conductive Oxide

TL;DR

This study demonstrates that Si doping in ZnO reduces strain and defect states, leading to enhanced optical transmission and conductance, making Si-doped ZnO a promising, moisture-resistant, ecofriendly transparent conductive oxide for electronics and solar cells.

Contribution

It reveals the beneficial effects of Si doping on strain reduction and defect decrease in ZnO, improving its optical and electrical properties for TCO applications.

Findings

Strain reduction correlates with decreased vacancy sites.

Doping increases optical transparency and conductivity.

Moisture sensitivity decreases with Si doping.

Abstract

Si doped ZnO has been reported to be a better conductor than pure ZnO. It is reported that carrier density increases and hence conductivity increases. However, the effect on optical transmission is yet not clear until our recent report [1]. Zn1-xSixO for x= 0, 0.013, 0.020 and 0.027 have been synthesized using sol-gel method (a citric acid-glycerol route) followed by solid state sintering. We found that there is a decrease in defect states due to Si doping. The correlation of strain to the decrement in vacancy sites is discussed in this report. In modern electronics and solar cell fabrication, transparent conductive oxides (TCOs) are important components which conduct electrically without absorbing visible light. Known TCOs are extremely costly and are composed of non-abundant elements. Search for new ecofriendly, cheap and sustainable TCOs has been a recent research of attraction. Keeping in mind that most solar cells are exposed to natural conditions, the humidity tolerance becomes a determining factor. We report that sensitivity to moisture decreases drastically while the conductivity and optical transparency increases with doping. The reduction of strain and improvement of transport properties results in increased conductivity of Si doped ZnO pellets, tempting us to envisage this material as a probable alternate TCO.