Partial hydrogenation induced interaction in a graphene–SiO₂interface: irreversible modulation of device characteristics

Abstract

The transformation of systematic vacuum and hydrogen annealing effects in graphene devices on the SiO surface is reported based on experimental and van der Waals interaction corrected density functional theory (DFT) simulation results. Vacuum annealing removes p-type dopants and reduces charged impurity scattering in graphene. Moreover, it induces n-type doping into graphene, leading to the improvement of the electron mobility and conductivity in the electron transport regime, which are reversed by exposing to atmospheric environment. On the other hand, annealing in hydrogen/argon gas results in smaller n-type doping along with a decrease in the overall conductivity and carrier mobility. This degradation of the conductivity is irreversible even the graphene devices are exposed to ambience. This was clarified by DFT simulations: initially, silicon dangling bonds were partially terminated by hydrogen, subsequently, the remaining dangling bonds became active and the distance between the graphene and SiO surface decreased. Moreover, both annealing methods affect the graphene channel including the vicinity of the metal contacts, which plays an important role in asymmetric carrier transport.

Phase‐Selective Synthesis of Ultrathin FeTe Nanoplates by Controllable Fe/Te Atom Ratio in the Growth Atmosphere

“…[ 44 ] In the simulations, clusters with different Fe atoms (e.g., Fe 2 Te 10 ) were placed on the center of quartz SiO 2 (0001) surface. [ 45 ] A SiO 2 slab with six‐layers‐Si‐atoms was used, and the up and bottom surfaces of the SiO 2 were passivated with hydrogen atoms to eliminate the effect of the interaction of the hanging bond. [ 46 ] The surface supercell was set to 3 × 3.…”

Bubble-Free Transfer Technique for High-Quality Graphene/Hexagonal Boron Nitride van der Waals Heterostructures

“…The longitudinal resistivity (ρ xx ) of back gate voltage (V g ) at 1.6 K exhibited the maxima, that is, the charge neutrality point was almost at V g = 0 V (Figure 4e), which signifies an undoped electronic state because of the absence of bubbles in the channel. 23,24 The inset in Figure 4e shows the Hall conductivity (σ xy ) as a function of V g of the device at T = 10 K and B = 6 T. Plateaus were observed at σ xy = (4Ne 2 )/h (where N, h, and e represent an integer number, a Planck constant, and an elementary charge, respectively), which implies the Landau quantization of BLG. 25 From the Hall measurement at 1.6 K, the charge carrier mobility was estimated at approximately 50 and 25 m 2 V −1 s −1 for electrons and holes, respectively.…”

Determining the Electron Scattering from Interfacial Coulomb Scatterers in Two-Dimensional Transistors

“…Remarkably, the α determined for sample B is smaller than that for samples A and C by 4 orders of magnitude at ΔV g = 0, indicating very small Coulomb scattering for the InSe FETs with the h-BN interlayer. As depicted in Figure 3b, the distance r for samples A and C can be assumed to be on the order of 0.1 nm by noting that the interaction between the InSe channel and the substrate is governed by the van der Waal force 36 and that the dominant carriers are induced adjacent to the InSe/ SiO 2 interface under an applied V g . 37 In contrast, while the bottom InSe interface of sample B is pristine, polydimethylsiloxane (PDMS) residue can be present on the top InSe interface, 5 suggesting that the r in sample B can be approximated by the thickness of the InSe channel, which is on the order of 10 nm (Supporting Information S1).…”