Band Gap Engineering of Hexagonal SnSe2 Nanostructured Thin Films for Infra-Red Photodetection

Emma P Mukhokosi,Saluru B Krupanidhi,Karuna K Nanda

doi:10.1038/s41598-017-15519-x

Emma P Mukhokosi, Saluru B Krupanidhi + Show 1 more

Open Access

https://doi.org/10.1038/s41598-017-15519-x

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Abstract

We, for the first time, provide the experimental demonstration on the band gap engineering of layered hexagonal SnSe2 nanostructured thin films by varying the thickness. For 50 nm thick film, the band gap is ~2.04 eV similar to that of monolayer, whereas the band gap is approximately ~1.2 eV similar to that of bulk for the 1200 nm thick film. The variation of the band gap is consistent with the the theoretically predicted layer-dependent band gap of SnSe2. Interestingly, the 400–1200 nm thick films were sensitiveto 1064 nm laser iradiation and the sensitivity increases almost exponentiallly with thickness, while films with 50–140 nm thick are insensitive which is due to the fact that the band gap of thinner films is greater than the energy corresponding to 1064 nm. Over all, our results establish the possibility of engineering the band gap of SnSe2 layered structures by simply controlling the thickness of the film to absorb a wide range of electromagnetic radiation from infra-red to visible range.

Highlights

SnSe2 thin films have been prepared by spin coating[20,21], spray pyrolysis[14,22,23], chemical vapour deposition(CVD)[15,18], molecular beam epitaxy[10], thermal evaporation of Sn and Se elements[24], and sputtering[25]
Our results suggest that the SnSe2 thin film can be explored as an excellent material for photodetection
We have fabricated and characterized layered SnSe2 thin films of different thickness on soda lime glass (SLG) substrate by DC sputtering of Sn metal target followed by selenisation

Summary

Introduction

SnSe2 thin films have been prepared by spin coating[20,21], spray pyrolysis[14,22,23], chemical vapour deposition(CVD)[15,18], molecular beam epitaxy[10], thermal evaporation of Sn and Se elements[24], and sputtering[25]. The band gap varied from 2.04 eV for 50 nm thick film to 1.20 eV for 1200 nm thick one. Our results establish the possibilty of engineering the band gap of SnSe2 layered structure by controlling the thickness of the film to absorb a wide range of electromagnetic radiation from infra-red to visible range

Methods

Results

Conclusion