Optically Coupled Methods for Microwave Impedance Microscopy

TL;DR

This paper introduces optically coupled methods for Microwave Impedance Microscopy that enable high-resolution, energy-resolved, and lifetime measurements of photoconductivity using modulated optical sources, improving signal quality and eliminating artifacts.

Contribution

It presents a novel approach combining optical modulation with MIM to measure photoconductivity, energy dependence, and carrier lifetimes at 50 nm resolution.

Findings

Demonstrated 50 nm resolution photoconductivity measurement

Achieved energy-resolved photoconductivity using broadband light source

Measured local photo-carrier lifetimes with pulsed optical source

Abstract

Scanning Microwave Impedance Microscopy (MIM) measurement of photoconductivity with 50 nm resolution is demonstrated using a modulated optical source. The use of a modulated source allows for measurement of photoconductivity in a single scan without a reference region on the sample, as well as removing most topographical artifacts and enhancing signal to noise as compared with unmodulated measurement. A broadband light source with tunable monochrometer is then used to measure energy resolved photoconductivity with the same methodology. Finally, a pulsed optical source is used to measure local photo-carrier lifetimes via MIM, using the same 50 nm resolution tip.