Mapping single-shot angle-resolved spectroscopic micro-ellipsometry with sub-5 microns lateral resolution

TL;DR

This paper introduces a novel spectroscopic micro-ellipsometer capable of single-shot, angle-resolved measurements with sub-5 micron lateral resolution, enabling detailed optical characterization of micro-structures.

Contribution

The authors develop and demonstrate a compact SME that integrates into standard microscopes, achieving high-resolution, rapid spectroscopic ellipsometry for micro-structures.

Findings

Accurate measurement of complex refractive index and thickness.

Lateral resolution down to 2 microns.

Effective characterization of layered 2D materials.

Abstract

Spectroscopic ellipsometry is a widely used optical technique both in industry and research for determining the optical properties and thickness of thin films. The effective use of spectroscopic ellipsometry on micro-structures is inhibited by technical limitations on lateral resolution and data acquisition rate. Here we introduce a spectroscopic micro-ellipsometer (SME), capable of measuring spectrally resolved ellipsometric data at many angles of incidence in a single-shot with a lateral resolution down to 2 microns. The SME can be easily integrated into generic optical microscopes by addition of a few stock optics. We demonstrate complex refractive index and thickness measurements by the SME which are in excellent agreement with a commercial spectroscopic ellipsometer. As an application for its accuracy and high lateral resolution, the SME can characterize the optical properties and number of layers of exfoliated transition-metal dichalcogenides and graphene, for structures that are a few microns in size.