Quantitative models for excess carrier diffusion and recombination in STEM-EBIC experiments on semiconductor nanostructures

TL;DR

This paper develops a quantitative model for excess carrier transport and recombination in nanostructures using STEM-EBIC, validated on complex oxide data, enabling precise diffusion length measurements at atomic scales.

Contribution

It introduces a generic analytical and finite element model for carrier dynamics in confined geometries applicable to STEM-EBIC experiments.

Findings

Successfully applied to SrTi0.995Nb0.005O3 data

Determined bulk diffusion length as 10.2 ± 0.1 nm

Demonstrated robustness and practicality of the model

Abstract

The increased complexity and reduced size of (opto-)electronic devices demands for quantitative descriptions of excess carrier transport and recombination via various mechanisms. In addition, experimental methods capable of resolving carrier dynamics on the nanometer scale are required. In this paper, we present a quantitative model of a confined geometry including recombination at two surfaces, which is very generic for electron beam induced current measurements in a scanning transmission electron microscope - a method which offers atomic scale spatial resolution. The model is based on analytical considerations as well as finite element simulations and underlying assumptions are subjected to an in-depth discussion. Finally, the successfull application to experimental data obtained on the complex oxide SrTi0.995Nb0.005O3 demonstrates the practicality and robustness of the approach, which enables the precise determination of its bulk diffusion length of L = 10.2 +- 0.1 nm.