Semi-shunt field emission in electronic devices

TL;DR

This paper introduces semi-shunts as needle-shaped metallic protrusions that cause strong electron emission, affecting photovoltaic device performance and potentially serving both as failure precursors and beneficial elements.

Contribution

It proposes the concept of semi-shunts, analyzes their effects on photovoltaic devices, and links stress-induced growth to device failure and potential mitigation strategies.

Findings

Semi-shunts cause low open circuit voltages in solar cells.

Stress can stimulate semi-shunt growth, leading to shunting failures.

Controllable semi-shunts may mitigate back field effects in photovoltaics.

Abstract

We introduce a concept of semi-shunts representing needle shaped metallic protrusions shorter than the distance between a device electrodes. Due to the lightening rod type of field enhancement, they induce strong electron emission. We consider the corresponding signature effects in photovoltaic applications; they are: low open circuit voltages and exponentially strong random device leakiness. Comparing the proposed theory with our data for CdTe based solar cells, we conclude that stress can stimulate semi-shunts' growth making them shunting failure precursors. In the meantime, controllable semi-shunts can play a positive role mitigating the back field effects in photovoltaics.