Versatility of the SiH–CdCl2 Heterostructure: Piezoelectricity, Photocatalysis, and Transistor Applications

Unlike bilayers or a few layer-thick materials, heterostructures are designer materials formed by assembling different monolayers in any desired sequence. As a result, heterostructures can be tailor-made for specific functionalities and applications. Here, we demonstrate the potential of the SiH–CdCl2 heterostructure for three types of applications. Piezoelectricity originates from interlayer charge transfer, and the heterostructure has an out-of-plane piezoelectric coefficient of −7.75 pC/m, comparable to and even higher than some recently reported 2D materials. The heterostructure is a potential candidate for photocatalytic water splitting by using solar energy. Not only does the band gap lie within the solar absorption spectrum, but a type-II band alignment also ensures electron and hole accumulation in separate monolayers, reducing their recombination. Tunnel field effect transistors (TFETs) made of heterostructures have a subthreshold swing (SS) comparable to that of reported transition metal dichalcogenide-based TFETs. SS below 60 mV/dec results as the device is modulated by band-to-band quantum tunneling, instead of thermionic emission dominated process in traditional metal-oxide-semiconductor field effect transistor. Overall, our work illustrates the multifunctional nature of heterostructures, which can be designed by leveraging the extensive database of layered materials to suit the specific needs of next-generation devices.