Probing surface recombination velocities in semiconductors using two-photon microscopy

TL;DR

This paper presents a three-dimensional analysis of two-photon microscopy data to accurately measure surface recombination velocities and minority-carrier lifetimes in semiconductors, accounting for complex geometries.

Contribution

It introduces an analytical framework that separates diffusion effects from recombination, applicable to various surface geometries, enhancing measurement accuracy.

Findings

Analytical solutions for different surface geometries.

Application to CdTe/ZnTe/Si heteroepitaxial data.

Improved separation of diffusion and recombination effects.

Abstract

The determination of minority-carrier lifetimes and surface recombination velocities is essential for the development of semiconductor technologies such as solar cells. The recent development of two-photon time-resolved microscopy allows for better measurements of bulk and subsurface interfaces properties. Here we analyze the diffusion problem related to this optical technique. Our three-dimensional treatment enables us to separate lifetime (recombination) from transport effects (diffusion) in the photoluminescence intensity. It also allows us to consider surface recombination occurring at a variety of geometries: a single plane (representing an isolated exposed or buried interface), two parallel planes (representing two inequivalent interfaces), and a spherical surface (representing the enclosing surface of a grain boundary). We provide fully analytical results and scalings directly amenable to data fitting, and apply those to experimental data collected on heteroepitaxial CdTe/ZnTe/Si.