In-plane anisotropic quantum confinement effect in ultrasmall SnS sheets

TL;DR

This paper reports the synthesis of ultrasmall SnS nanosheets exhibiting in-plane anisotropic quantum confinement effects, revealing valley-dependent optical properties and potential for advanced electronic and optoelectronic applications.

Contribution

It introduces a novel synthesis method for highly crystalline ultrasmall SnS sheets and demonstrates their anisotropic quantum confinement effects and valley-dependent photoluminescence.

Findings

Ultrasmall SnS exhibits increased band gaps due to quantum confinement.

SnS quantum dots show excitation energy dependent photoluminescence.

The work highlights potential applications in electronics and optoelectronics.

Abstract

Black phosphorus (BP) analogous tin(II) sulfide (SnS) has recently emerged as an attractive building block for electronic devices due to its highly anisotropic response. Two-dimensional (2D) SnS has shown to exhibit in-plane anisotropy in optical and electrical properties. However, the limitations in growing ultrasmall structures of SnS hinder the experimental exploration of anisotropic behavior in low dimension. Here, we present an elegant approach of synthesizing highly crystalline nanometer-sized SnS sheets. Ultrasmall SnS exhibits two distinct valleys along armchair and zig-zag directions due to in-plane structural anisotropy like bulk SnS. We show that in such SnS nanosheet dots, the band gaps corresponding to two valleys are increased due to quantum confinement effect. We particularly observe that SnS quantum dots (QDs) show excitation energy dependent photoluminescence (PL), which originates from the two nondegenerate valleys. Our work may open up an avenue to show the potential of SnS QDs for new functionalities in electronics and optoelectronics.