Quantum corrections to conductivity in Si doped ZnO thin films

TL;DR

This study investigates quantum corrections to electrical conductivity in Si-doped ZnO thin films, revealing weak localization effects and temperature-dependent resistivity behavior across various doping levels.

Contribution

It provides a detailed analysis of quantum corrections to conductivity in Si-doped ZnO films, highlighting the role of weak localization effects at different doping concentrations.

Findings

Negative magnetoresistance indicates weak localization.

Quantum correction models fit resistivity data well.

Temperature coefficient of resistivity varies with doping level.

Abstract

Si doped ZnO thin films with Si concentrations ranging from 0.4 to 10 % have been grown by sequential pulsed laser deposition on sapphire substrates. The resistivity of the films first decreased from ~ 6.6x10-3 to 4.7x10-4 ohm-cm as the Si concentration was increased from ~ 0.4 to 2% and then it increased with further increase in Si concentration. The electron concentrations in the films were in the range from 3x1019 to 4x1020 cm-3 showing their degenerate nature. However, temperature dependent resistivity measurements in the range from 300 to 4.2 K revealed negative temperature coefficient of resistivity (TCR) for the 0.4, 6 and 10% Si doped ZnO films in the entire measurement temperature range. The 0.6, 0.9 and 2% Si doped films showed a transition from negative to positive TCR with increasing temperature. The negative magnetoresistance found in the films at low temperatures and 0.5 T magnetic field pointed to weak localization as the dominant contributor towards negative TCR. A quantitative fit of the temperature dependent resistivity data for all the films could be obtained by considering the quantum correction to conductivity arising due to disorder induced weak localization effect.