The electronic and interfacial properties of a vdW heterostructure composed of penta-PdSe₂and biphenylene monolayers

Abstract

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.

Schottky-Barrier-Free vdW Contact in a 2D Penta-NiN2/Biphenylene Network Heterostructure

“…To examine the interface stability of this stack, we calculate its binding energy of E b = 0.05 eV/Å 2 (80 μJ/cm 2 ) using the equation E b = – [( E H – E x – E y )/ A ], here E H is the total energy of the penta-NiN 2 /BPN heterostructure, E x and E y are the energies of the free-standing penta-NiN 2 and BPN monolayers, respectively, and A is the total supercell area of the penta-NiN 2 /BPN heterostructure. Our results are close to those of the typical vdW crystals such as graphite [ E b = 0.02 eV/Å 2 (32 μJ/cm 2 ) and d = 3.60 Å], hexagonal BN [ E b = 0.04 eV/Å 2 (64 μJ/cm 2 ) and d = 3.30 Å], and some recently reported pentagon-based vdW heterostructures such as penta-graphene/graphene with E b = 0.06 eV/Å 2 (96 μJ/cm 2 ) and d = 3.14 Å and PdSe 2 /BPN with E b = 0.06 eV/Å 2 (96 μJ/cm 2 ) and d = 3.40 Å, indicating the interface stability of the atomically flat penta-NiN 2 /BPN heterostructure bound by weak vdW interactions.…”

“…For penta-NiN 2 /BPN, it is worth noting that the upward (downward) shifting of the VBM (CBM) leads to Φ SB values of −0.02 eV for Φ h and 1.01 eV for Φ e , implying the formation of a Schottky-barrier-free p -type contact, which is remarkably different from that of conventional pentagon-based heterostructures, ,, and highly desired in metal–semiconductor device applications. , Therefore, it is robust to conclude that the BPN sheet can spontaneously inject holes into the penta-NiN 2 sheet upon formation of a vdW contact with zero-barrier contact resistance.…”

“…Although there is no Φ SB at the vertical interface and no band bending at the lateral interface of the penta-NiN 2 /BPN system, the tunneling barrier can still exist at the vertical interface because no strong orbital overlapping occurs at the heterojunction interface . In a vdW contact, the tunneling probability of charge carriers can be calculated by using the Wentzel–Kramer–Brillouin (WKB) approximation, , TP = exp ( − 2 w TB ℏ 2 m Φ TB ) where Φ TB and w TB represent the height and width of the electrostatic potential, m is the electronic mass, and ℏ is the reduced Planck’s constant. The Φ TB and w TB are calculated to be 3.4 eV and 1.6 Å, respectively, from the electrostatic potential profile (see Figure b), and we obtained a TP of 5% in the penta-NiN 2 /BPN heterostructure based on eq .…”

“…Although there is no Φ SB at the vertical interface and no band bending at the lateral interface of the penta-NiN 2 /BPN system, the tunneling barrier can still exist at the vertical interface because no strong orbital overlapping occurs at the heterojunction interface. 45 In a vdW contact, the tunneling probability of charge carriers can be calculated by using the Wentzel−Kramer−Brillouin (WKB) approximation, 41,45 = i k j j j y…”

Contact evaluation of the penta-PdPSe/graphene vdW heterojunction: tuning the Schottky barrier and optical properties

“…Fig. 2(c) shows the binding energy E b (eV) versus the interlayer distance (Å) where the calculated binding energy ( E b ∼ 0.025 eV Å −2 ) and interlayer distance ( d = 3.6 Å) of the penta-PdPSe/G system are very close to those of the typical vdW crystals such as graphite [ E b = 0.02 eV Å −2 and d = 3.60 Å], 43 hexagonal BN ( E b = 0.04 eV Å −2 and d = 3.30 Å), and some recently reported vdW systems such as PG/graphene ( E b = 0.06 eV Å −2 and d = 3.14 Å), 44 PdSe 2 /BPN ( E b = 0.06 eV Å −2 and d = 3.40 Å), 45 and PdSe 2 /graphene ( E b = 0.02 eV Å −2 and d = 3.60 Å), 46 suggesting the stability of the penta-PdPSe/G as a vdW contact. Furthermore, the thermal stability of the penta-PdPSe/G system is investigated at 500 K, and fluctuations of the total potential energy are presented in Fig.…”