Influence of the statistical shift of Fermi level on the conductivity behavior in microcrystalline silicon

TL;DR

This study investigates how the Fermi level's statistical shift influences the electrical conductivity in microcrystalline silicon, explaining both Meyer-Neldel rule and anti-MNR behaviors through a band tail transport model.

Contribution

It introduces a statistical shift model to explain conductivity behaviors in microcrystalline silicon, supported by experimental data and literature analysis.

Findings

MNR and anti-MNR behaviors depend on microstructure.

The statistical shift model explains both MNR and anti-MNR.

Calculated parameters are consistent across various microstructures.

Abstract

The electrical conductivity behavior of highly crystallized undoped hydrogenated microcrystalline silicon films having different microstructures was studied. The dark conductivity is seen to follow Meyer Neldel rule (MNR) in some films and anti MNR in others, depending on the details of microstructural attributes and corresponding changes in the effective density of states distributions. A band tail transport and statistical shift of Fermi level are used to explain the origin of MNR as well as anti-MNR in our samples. We present the evidence of anti-MNR in the various experimental transport data of microcrystalline silicon materials reported in literature and analyze these data together with ours to show the consistency and physical plausibility of statistical shift model. The calculated MNR parameters and other significant material parameters derived therefrom are tenable for a wide microstructural range of the microcrystalline silicon system.