Motivated by the recent synthesis of the pentagonal PdSe 2 sheet [J. Am. Chem. Soc. 2017, 139, 14090], here using first-principles calculations, we have systematically carried out simulations to investigate the PdSe 2 sheet's performance as a channel material when in contact with metal surfaces and graphene. We find that the PdSe 2 sheet can almost retain its pentagonal feature with small distortions when in contact with Au(111), Ag(111), Cu(111), and Pb(111) surfaces. However, it is severely distorted on the Ti(0001) surface undergoing metallization. Band structure analysis suggests that the vertical Schottky barrier disappears in all of the metal contacts. Au, Ag, Cu, Ti, and Pb are of the Schottky type contacts with barriers of 0.62, 0.87, 0.79, 0.58, and 0.76 eV in the lateral direction for electrons, whereas both monolayer and bilayer PdSe 2 maintain their intrinsic properties when in contact with graphene forming a weak van der Waals interaction with no charge transfer between the two surfaces. Our study provides insights into selecting high-performance monolayer PdSe 2 device evaluations based on the orbital overlap, tunneling barrier, and Schottky barrier.

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Novel properties of penta-graphene (PG) have stimulated great interest in exploring its potential for device applications. Here, we systematically study the interfacial properties of the heterojunctions constructed by stacking PG on several metal substrates (Ag, Al, Au, Cr, Cu, Pd, and Ti), which are commonly used in field-effect transistors. We consider PG as the channel material because of its semiconducting feature, while treating the metal surfaces as the electrodes. Based on first principles calculations, we show that PG preserves its pentagonal feature with some small distortions when deposited on the metal substrates but undergoes metallization due to the chemical bonding between PG and the metal surfaces. We evaluate the device potential of these PG-metal contacts by studying their tunneling barriers, orbital overlaps, and Schottky barriers. We find that PG forms an n-type Schottky barrier when in contact with Al, Cu, and Ti, but forms a p-type Schottky barrier when supported on Ag, Au, Cr, and Pd. Our study sheds light on the design and fabrication of PG-based electronic devices.

The vdW PdSe2/biphenylene network heterostructure with n-type Schottky contact and negative band-bending is theoretically designed to carry current in n-channel field effect transistor devices.

Although the electronics and optoelectronics based on two-dimensional (2D) SnS have attracted great interest, their development is hindered by the large contact resistance at the interface of the metal−semiconductor junction. In this work, using first-principles calculations, we evaluate the contact performance in a van der Waals heterostructure composed of 2D SnS and TaS 2 . We demonstrate that holes can freely transfer from the electrode to the channel as a consequence of the Schottky-barrier-free interface as well as an upward band bending. Moreover, we show that the intrinsic properties of the SnS monolayer are well-preserved in the heterojunction, which is different from those of contact with metal surfaces. An enhanced optical response is also observed as compared with the freestanding sheet. Given the recent experimental synthesis of the SnS−TaS 2 superlattice, this study enhances the understanding of the interface properties of SnSbased metal contact, which is essential for future device applications.