Preparation of single-phase SnSe thin-films and modification of electrical properties via stoichiometry control for photovoltaic application

Single-phase SnSe thin films were prepared via thermal co-evaporation using a Se thermal cracker. By carefully tuning the stoichiometry of the SnSe, we found that the composition range of single phase SnSe is very narrow, a Se/Sn ratio of 0.95–0.99; outside of this range secondary phases (metallic S...

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Bibliographic Details
Published in:Journal of alloys and compounds 2017-10, Vol.722, p.474-481
Main Authors: Jeong, Giuk, Kim, Jekyung, Gunawan, Oki, Pae, Seong Ryul, Kim, Soo Hyun, Song, Jae Yong, Lee, Yun Seog, Shin, Byungha
Format: Article
Language:English
Subjects:
Antimony
Carrier density
Electric properties
Electrical properties
Electronic band structure
Electronic properties
Evaporation
Inorganic materials
Ionization
Photoconductivity and photovoltaics
Photovoltaic cells
Stoichiometry
Studies
Thin films
Tin selenide
Tuning
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Summary:Single-phase SnSe thin films were prepared via thermal co-evaporation using a Se thermal cracker. By carefully tuning the stoichiometry of the SnSe, we found that the composition range of single phase SnSe is very narrow, a Se/Sn ratio of 0.95–0.99; outside of this range secondary phases (metallic Sn or SnSe2) formed. Electrical properties were found to be very sensitive to even small changes in the stoichiometry. Three orders of magnitude difference in the carrier concentration was observed within the stoichiometry range for single-phase SnSe, which can be explained by changes in the shallow level defect density. To further control carrier concentration, we introduced In and Sb as counter-dopants into the SnSe thin films and found that they were deep level donors with the ionization fraction of ∼10−4. Finally, we demonstrate the potential of SnSe thin films as an absorber layer in photovoltaic applications. Our study demonstrates the importance of fine-tuning stoichiometry of SnSe to achieve desired electrical properties. [Display omitted] •Single phase SnSe thin films are fabricated via thermal co-evaporation method.•The range of the Se/Sn ratio for single phase SnSe is 0.95–0.99.•Also, carrier concentration of films varied dramatically (1015–1017 cm−3).•Sb or In were found to work as counter-dopants to p-type SnSe.•Working photovoltaic device based on SnSe thin films was reported.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2017.06.094