Approximate Theory of Temperature Coefficient of Resistivity of Amorphous Semiconductors

TL;DR

This paper presents an approximate theoretical model for the temperature coefficient of resistivity in amorphous semiconductors, aligning well with experimental data and explaining a long-standing experimental anomaly.

Contribution

It introduces a new explicit theory based on the Microscopic Response Method, incorporating approximations for lattice dynamics and electronic states to predict TCR and conductivity.

Findings

The theory agrees with experimental data on a-Si:H and a-Ge:H.

It predicts a 'kink' in the log(σ) vs. 1/T curve due to localized-extended transitions.

Provides explicit formulas for conductivity and TCR based on accessible parameters.

Abstract

In this paper, we develop an approximate theory of the temperature coefficient of resistivity (TCR) and conductivity based upon the recently proposed Microscopic Response Method. By introducing suitable approximations for the lattice dynamics, localized and extended electronic states, we produce new explicit forms for the conductivity and TCR, which depend on easily accessible material parameters. The theory is in reasonable agreement with experiments on a-Si:H and a-Ge:H. A long-standing puzzle, a \textquotedblleft kink\textquotedblright\ in the experimental $% \log_{10}\sigma $ vs. 1/T curve, is predicted by the theory and attributed to localized to extended transitions, which have not been properly handled in earlier theories.