Electron beam induced current in the high injection regime

TL;DR

This paper develops an analytic model for Electron Beam Induced Current (EBIC) in high injection regimes, predicting charge collection behavior when generation rates surpass extraction rates, verified by simulations and experimental data.

Contribution

The paper introduces a simple analytic model for EBIC response in high injection conditions, accounting for charge accumulation and screening effects, and validates it with numerical simulations and experimental comparisons.

Findings

Model accurately predicts EBIC lineshape in high injection regimes.

Charge accumulation and screening significantly influence EBIC response.

Experimental data align with the 3D model predictions.

Abstract

Electron beam induced current (EBIC) is a powerful technique which measures the charge collection efficiency of photovoltaics with sub-micron spatial resolution. The exciting electron beam results in a high generation rate density of electron-hole pairs, which may drive the system into nonlinear regimes. An analytic model is presented which describes the EBIC response when the {\it total} electron-hole pair generation rate exceeds the rate at which carriers are extracted by the photovoltaic cell, and charge accumulation and screening occur. The model provides a simple estimate of the onset of the high injection regime in terms of the material resistivity and thickness, and provides a straightforward way to predict the EBIC lineshape in the high injection regime. The model is verified by comparing its predictions to numerical simulations in 1 and 2 dimensions. Features of the experimental data, such as the magnitude and position of maximum collection efficiency versus electron beam current, are consistent with the 3 dimensional model.