Anomalous Scaling Exponents of Capacitance-Voltage Characteristics

TL;DR

This paper reveals that the capacitance of thin film devices scales as V^-2, challenging the traditional V^-0.5 assumption in Mott-Schottky analysis, with significant implications for device parameter extraction.

Contribution

It introduces a simple analytical model predicting a V^-2 scaling law for capacitance, supported by numerical simulations, revising the understanding of CV characteristics in thin film devices.

Findings

Capacitance scales as V^-2 in thin film devices.

Existing literature already contains evidence of this scaling.

Impacts parameter extraction methods for various optoelectronic devices.

Abstract

Capacitance-Voltage (CV) measurements along with the Mott-Schottky (MS) analysis are widely used for characterization of material and device parameters. Using a simple analytical model, supported by detailed numerical simulations, here we predict that the capacitance of thin film devices scale as V^-2 (V is the applied potential), instead of the often used V^-0.5 dependence of MS analysis- with significant implications towards extraction of parameters like doping density, built-in voltage, etc. Surprisingly, we find that the predicted trends are already hidden in multiple instances of existing literature. As such, our results constitute a fundamental contribution to semiconductor device physics and are directly applicable and immediately relevant to a broad range of optoelectronic devices like organic solar cells, perovskite-based solar cells, and LEDs, thin film a-Si devices, etc.