The emerging Janus Ga 2 SeTe with an asymmetric structure has attracted a great deal of research interest. In this paper, we construct the van der Waals heterostructures (vdWHs) of monolayer Janus Ga 2 SeTe and germanene (Ge) and named their two stacking modes as Te/Ge vdWH and Se/Ge vdWH. We find that Ge/Ga 2 SeTe vdWHs in both stacking modes form n-type Schottky contacts. Furthermore, the Schottky barrier height and Schottky contact type in Ge/Ga 2 SeTe are modulated through interlayer distances and electric fields, which lead to a transition from n-type to p-type Schottky contacts or ohmic contacts. In particular, the weak interaction between the two monolayers leads to the creation of a band gap in the Dirac cone. When a compressive strain in the z direction is applied to the Se/Ge heterostructure, Ge has a larger band gap. The results of our work can provide valuable guidance for the design of controllable Schottky nanodevices and high-performance optoelectronic devices based on Ge/Ga 2 SeTe vdWHs.
Given the recent experimental synthesis of the two-dimensional (2D) semiconductor material WSi<sub>2</sub>N<sub>4</sub> (WSN) and the 2D metal material MoSH (MSH), we constructed a metal-semiconductor MSH/WSN Schottky-junction. In practical applications of metal-semiconductor contact, the presence of the Schottky barrier degrades the device performance severely. Therefore, it is crucial to obtain a smaller Schottky barrier height or even an Ohmic contact. In this paper, first-principles calculations were used to investigate the variation of the Schottky barrier in MSH/WSN Schottky-junction under the external electric field and the biaxial strain. The results show that both external electric field and biaxial strain can effectively modulate the Schottky barrier of the MSH/WSN Schottky-junction. The dynamic switching between the p-type Schottky contact and the n-type Schottky contact can be achieved under the positive external electric field in the MSH/WSN Schottky-junction. Under the negative external electric field, the MSH/WSN Schottky-junction can be modulated to realize the transition from the Schottky contact to the Ohmic contact. The large biaxial strain can also induce the MSH/WSN Schottky-junction to realize the transition between the p-type Schottky contact and the n-type Schottky contact. This work may provide theoretical guidance for Schottky functional devices and field-effect transistors based on WSN semiconductor.
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