Exciton pumping across type-I gallium chalcogenide heterojunctions
2016; IOP Publishing; Volume: 27; Issue: 6 Linguagem: Inglês
10.1088/0957-4484/27/6/065203
ISSN1361-6528
AutoresHui Cai, Jun Kang, Hasan Şahin, Bin Chen, Aslıhan Süslü, Kedi Wu, F. M. Peeters, Xiuqing Meng, Sefaattin Tongay,
Tópico(s)Chalcogenide Semiconductor Thin Films
ResumoQuasi-two-dimensional gallium chalcogenide heterostructures are created by transferring exfoliated few-layer GaSe onto bulk GaTe sheets. Luminescence spectroscopy measurements reveal that the light emission from underlying GaTe layers drastically increases on heterojunction regions where GaSe layers make contact with the GaTe. Density functional theory (DFT) and band offset calculations show that conduction band minimum (CBM) (valance band maximum (VBM)) values of GaSe are higher (lower) in energy compared to GaTe, forming type-I band alignment at the interface. Consequently, GaSe layers provide photo-excited electrons and holes to GaTe sheets through relatively large built-in potential at the interface, increasing overall exciton population and light emission from GaTe. Observed results are not specific to the GaSe/GaTe system but observed on GaS/GaSe heterolayers with type-I band alignment. Observed experimental findings and theoretical studies provide unique insights into interface effects across dissimilar gallium chalcogenides and offer new ways to boost optical performance by simple epitaxial coating.
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