Modulation of contact types and Schottky barrier in Ti3C2T2/TiSi2N4 (T = O or OH) van der Waals heterostructures by biaxial strain and external electric field

A new kind of two-dimensional semiconductor, MA2Z4, has shown exceptional electrical and mechanical properties, that make it suitable for use as a semiconductor device. In this paper, metallic Ti3C2T2 (T = O or OH) and semiconductor TiSi2N4 van der Waals heterostructures are constructed, and their interfacial characteristics are investigated under the effect of biaxial strain and external electric field. Due to the different terminations on Ti3C2 surfaces, Ti3C2O2/TiSi2N4 exhibits an n-type Schottky contact whose Schottky barrier is 0.718 eV, and Ti3C2(OH)2/TiSi2N4 exhibits an Ohmic contact. Furthermore, the Ti3C2O2/TiSi2N4 heterojunction can be changed from n-type Schottky contact to p-type Schottky contact by applying biaxial strain or external electric field, while the Ti3C2(OH)2/TiSi2N4 heterojunction keeps an Ohmic contact unchanged during the process. Our results demonstrate their potential as candidates for tunable nanoelectronic devices and field-effect transistors.