Depletion region surface effects in electron beam induced current measurements

Published

September 7, 2016

Author(s)

Paul M. Haney, Heayoung Yoon, Benoit H. Gaury, Nikolai B. Zhitenev

Abstract

Electron beam induced current (EBIC) is a powerful characterization technique which offers the high spatial resolution needed to study polycrystalline solar cells. Ideally, an EBIC measurement reflects the spatially resolved quantum efficiency of the device. Cross-sectional EBIC experiments on Si photovoltaic cells prepared by cleaving and focused ion beam polishing show that, depending on the sample preparation, the maximum efficiency of carrier collection may be signi cantly less than 100 % and varies throughout the depletion region. The reduced EBIC collection efficiency is inconsistent with the short circuit current density of the devices. Motivated by these experiments, we study the effect of surface recombination on EBIC, and consider charge-neutral surfaces and charged surfaces with Fermi level pinning. For neutral surfaces we present a simple analytical formula which describes the numerical data well, while the charged surface response depends qualitatively on the location of the surface Fermi level relative to the bulk Fermi level. We find the experimental data is most consistent with a charged surface, and discuss the implications for EBIC experiments on polycrystalline materials.

Citation

Journal of Applied Physics

Volume

120

Issue

9

Pub Type

Journals

Download Paper

https://doi.org/10.1063/1.4962016

Keywords

photovoltaics, electron beam induced current

Citation

Haney, P. , Yoon, H. , Gaury, B. and Zhitenev, N. (2016), Depletion region surface effects in electron beam induced current measurements, Journal of Applied Physics, [online], https://doi.org/10.1063/1.4962016 (Accessed April 25, 2024)