Silicite: the layered allotrope of silicon

TL;DR

This paper predicts two new stable layered silicon phases, silicites, with unique electronic properties and potential for photovoltaic use, based on first-principles calculations.

Contribution

It introduces two novel thermodynamically stable layered silicon allotropes with unique stacking and electronic properties, expanding the understanding of silicon's structural diversity.

Findings

Silicites have wider indirect band gaps than silicon crystal.

They exhibit increased visible light absorption.

The study provides atomic-scale mechanisms for multilayer silicene and silicite growth.

Abstract

Based on first-principles calculation we predict two new thermodynamically stable layered-phases of silicon, named as silicites, which exhibit strong directionality in the electronic and structural properties. As compared to silicon crystal, they have wider indirect band gaps but also increased absorption in the visible range making them more interesting for photovoltaic applications. These stable phases consist of intriguing stacking of dumbbell patterned silicene layers having trigonal structure with $\sqrt{3} \times \sqrt{3}$ periodicity of silicene and have cohesive energies smaller but comparable to that of the cubic diamond silicon. Our findings also provide atomic scale mechanisms for the growth of multilayer silicene as well as silicites.