Interfacial properties of penta-graphene-metal contacts

Abstract

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.

Performance of the Pentagonal PdSe2 Sheet as a Channel Material in Contact with Metal Surfaces and Graphene

“…Following the Schottky−Mott rule, 24 metals with either a large work function (WF) or minimal WF are desired to form a low-energy barrier contact reported in our previous work. 26 Five metals, counting silverAg, goldAu, copperCu, chromiumCr, leadPb, and titaniumTi were selected as the contact electrode because these are usually used in transistor applications and covers a wide range of WFs. 25 To match the PdSe 2 ML, we choose closed pack surface (111) for Ag, Au, Pd, and Cu contacts, and (0001) surface for Ti, as these are the prevailing orientations found in other experimental and theoretical studies, and they form minimal lattice mismatch.…”

“…We then build the heterojunctions by stacking PdSe 2 and metal surfaces vertically together forming top contacts following our previous work. 26 Because the lattice parameters of PdSe 2 and the chosen metal electrodes are different from each other, special care is needed to create an appropriate interface, for that, we have used our in-house code 26 to generate the heterojunctions. Using the code, the lattice mismatch percentage is set under 3% and the atom concentration is also under 300 to keep the lattice strain negligible.…”

“…For structural optimization, all studied heterojunctions are relaxed until the force and energy less than 0.01 eV/Å and 1 × 10 −6 eV, respectively. 26…”

“…In either case, realizing a low-resistant metal contact is the most significant defiance that masks the intrinsic electronic properties of a 2D-semiconductor." 26 To fulfill the need for a viable doping method, it is vital to find a suitable metal substrate to contact a 2D semiconductor.…”

Structural stability of single-layer PdSe2 with pentagonal puckered morphology and its nanotubes

“…Though some unstable materials can be stabilized by a suitable substrate, this is not the case for penta-graphene because of the large internal stress. 16 While theoretical calculations have already highlighted its instability, dozens of authors and journals continue to report (see, for example [34][35][36] and many others) promising, unique or rather fantastic properties of many penta-structures consisting of other elements misleading key researches for years.…”