Thickness-dependent Dielectric Constant of Few-layer In2Se3 Nano-flakes

TL;DR

This study investigates how the dielectric constant of few-layer In2Se3 nano-flakes varies with thickness, combining experimental measurements and theoretical calculations to reveal a monotonic increase that saturates at bulk values.

Contribution

It provides the first combined experimental and theoretical analysis of thickness-dependent dielectric constant in In2Se3 nano-flakes, highlighting the layer-dependent dielectric behavior.

Findings

Dielectric constant increases with layer number and saturates at 6-8 layers.

Experimental and theoretical results show consistent layer-dependent dielectric trends.

Results are applicable to other layered 2D semiconductors.

Abstract

The dielectric constant or relative permittivity of a dielectric material, which describes how the net electric field in the medium is reduced with respect to the external field, is a parameter of critical importance for charging and screening in electronic devices. Such a fundamental material property is intimately related to not only the polarizability of individual atoms, but also the specific atomic arrangement in the crystal lattice. In this letter, we present both experimental and theoretical investigations on the dielectric constant of few-layer In2Se3 nano-flakes grown on mica substrates by van der Waals epitaxy. A nondestructive microwave impedance microscope is employed to simultaneously quantify the number of layers and local electrical properties. The measured dielectric constant increases monotonically as a function of the thickness and saturates to the bulk value at around 6 ~ 8 quintuple layers. The same trend of layer-dependent dielectric constant is also revealed by first-principle calculations. Our results of the dielectric response, being ubiquitously applicable to layered 2D semiconductors, are expected to be significant for this vibrant research field.