Effect of thickness on optical properties of InSe/In2Se3 heterojunction

This study focuses on exploring the optical and electrical properties of indium selenide/indium diselenide heterojunctions of varying thicknesses. High-quality thin-layer samples of indium selenide and indium diselenide were prepared using a mechanical exfoliation method. Characterization of these heterojunctions through Raman spectroscopy and fluorescence spectroscopy revealed the significant influence of the layer thickness on the electron transfer mechanisms between the materials. The application direction was determined from the output characteristic curves and photocurrent effects. The experimental results emphasize the controllability of electron transfer and underscored the importance of material thickness in optimizing the design of optoelectronic devices, highlighting the advantages of this heterojunction device for weak light detection. In particular, it was found that heterojunctions with different contrasts can be divided into two states based on their photoluminescence (PL) intensity. For example, in the indium selenide (InSe)/indium diselenide (In2Se3) heterojunction with R = 0.075, the PL intensity of InSe was ∼14 000, whereas that of In2Se3 was ∼900. The fluorescence intensity of the heterojunction before transfer was ∼5000, showing a decreasing trend after transfer. In contrast, for the heterojunction with R = 0.475, the PL intensity of InSe is ∼11 000 and that of In2Se3 is ∼9000, with the PL intensity of the heterojunction increasing to ∼18 000. In addition, at Vds > 0.5, the device formed a junction. This study provides valuable insights into enhancing the heterojunction performance and offers a new perspective in the field of optoelectronic devices.