High-performance photoelectric and self-powered properties of a p–n GaSe/SnS2 heterojunction by a built-in electric field

Abstract

The advancement and exploration of multifunctional, self-powered devices are significantly enhanced by the van der Waals (vdW) heterojunctions formed between two-dimensional (2D) materials. In this work, a GaSe/SnS₂ heterojunction was constructed using a GaSe monolayer and SnS₂ monolayer. The GaSe/SnS₂ heterojunction exhibited a steady structure and type-II arrangement. The presence of potential drop (E_P) in the heterojunction drives the formation with a built-in electric field, resulting in the ability to operate without the need for bias voltage and attainment of self-powered performance. The GaSe/SnS₂ heterojunction exhibited enhanced photoresponsivity in the ultraviolet region compared to a single material. The GaSe/SnS₂ heterojunction also achieved a maximum photocurrent of 3.9 a₀² per photon, and the measured extinction ratio was 38.3 at photon energies of 4.1 eV and 3.2 eV, respectively. In addition, vertical and biaxial strains played a crucial role in influencing the band structures and optoelectronic characteristics of the GaSe/SnS₂ heterojunction. We verified the experimentally discovered p–n type heterojunction, explained the high performance of GaSe/SnS₂, and theoretically analyzed the self-powered capability and the modulation effect of strain on the GaSe/SnS₂ heterojunction. This work provides insights into the self-powered properties and strain modulation in 2D vdW heterojunctions and contributes to the development of multifunctional optoelectronic devices.