Reactive sputtering of SnS thin films using sulfur plasma and a metallic tin target: achieving stoichiometry and large grains

TL;DR

This paper introduces a safer, efficient reactive sputtering method using sulfur plasma and a tin target to produce high-quality, large-grain SnS thin films with potential for flexible photovoltaic devices.

Contribution

The study develops a novel sulfur plasma-assisted reactive sputtering process for fabricating stoichiometric SnS thin films with large grains at low temperatures, avoiding toxic gases.

Findings

Achieved dense, single-phase SnS films with micron-scale grains.

Demonstrated high in-plane Hall mobility of 13 cm² V⁻¹ s⁻¹.

Enabled room-temperature film fabrication for flexible device applications.

Abstract

This study presents a novel method for fabricating stoichiometric SnS thin films with large grain sizes via reactive sputtering using a metallic Sn target and sulfur plasma (S-plasma). Unlike conventional approaches that rely on toxic H2S gas, this method employs a S-plasma to enhance sulfur reactivity and mitigate sulfur deficiencies during film deposition. By optimizing the balance between the sputtering conditions of the Sn target and the supply conditions of the S-plasma, dense single-phase SnS thin films with micron-scale grain sizes were achieved at a substrate temperature of 300 degree C, achieving an in-plane Hall mobility of 13 cm2 V-1 s-1. Furthermore, crystalline SnS thin films were fabricated even on a room-temperature substrate, enabling potential applications in flexible devices with heat-sensitive substrates. These findings demonstrate the effectiveness of S-plasma in advancing SnS thin film fabrication, providing a safer and more efficient route to high-performance photovoltaic materials.