Tunable optical and electronic properties of Janus monolayers Ga2SSe, Ga2STe, and Ga2SeTe as promising candidates for ultraviolet photodetectors applications

Hoi D.Bui, Hamad RahmanJappor, Nguyen N.Hieu



Janus Ga2STe, Ga2STe, and Ga2SeTe monolayers have been designed composed of GaS, GaSe, and GaTe monolayers and study their electronic and optical properties using the density functional theory. Interestingly, our results revealed that the Ga2STe and Ga2SeTe have desirable direct band gaps of 0.90 and 1.21 eV, respectively, while Ga2STe has an indirect gap of 2.02 eV, all of the energy bandgaps are smaller than those of the perfect monolayers. The optical absorption confirms a strong absorption of the light in the range between 3 and 21 eV. More importantly, the optical absorption of Janus structures begins in the visible region with absorption coefficients larger than 104 cm−1. Combining the optical and electronic properties, Ga2STe, Ga2STe, and Ga2SeTe monolayers have a great possibility to be used as ultraviolet detectors and photovoltaic absorbers applications. Consequently, the present work offers significant guidelines for the design of optoelectronic devices that made of layered Janus structures and provides useful guidance for further expanding the practical application range of these materials.

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