Study of homogeneous and heterogeneous junctions of 2D MoS₂ on flexible substrates for improved functionalities in piezotronics

Strain gated electronics have gained attention in research for the development of interactive electronic systems. Combined electronic and sensor capabilities for interactive electronics can be achieved using semiconducting materials that are piezoelectric, also called piezotronic materials. Two-dimensional (2D) materials are apt for piezotronic devices because of their tunable electronic properties, and many of them are found to exhibit piezoelectricity.  The piezo-potentials generated from a single material have limited functionalities. The junctions of 2D materials can tap the be piezo-potentials effectively and can suffice the switching behavior. A homogenous junction can be formed between a monolayer and a multilayer of the same material, whereas the heterojunction with two different 2D materials. Here, we present the comparison of homogeneous and heterogeneous junctions of 2D MoS₂ for piezotronics in terms of process complexity and efficiency. Devices are fabricated on flexible substrates to study the strain-dependent electrical and optical characteristics. We have also proposed detailed methods to fabricate and test these devices on flexible substrates reliably. These devices have shown improved performance and can help realize efficient strain-gated electronics.