arXiv subjects

Tianhua Yu

Publications and source records attributed to Tianhua Yu.

3 recordsLinked to original sources

arXiv2011

Chemical Vapor Deposition-Assembled Graphene Field-Effect Transistor on Hexagonal Boron Nitride

We investigate key electrical properties of monolayer graphene assembled by chemical-vapor-deposition (CVD) as impacted by supporting substrate material. Graphene field-effect transistors (GFETs) were fabricated with carbon channel placing directly on hexagonal boron nitride (h-BN) and SiO2, respectively. Small-signal transconductance (gm) and effective carrier mobility (μeff) are improved by 8.5 and 4 times on h-BN, respectively, as compared with that on SiO2. Compared with GFET with exfoliated graphene on SiO2, gm and μeff measured from device with CVD graphene on h-BN substrate exhibits comparable values. The experiment demonstrates the potential of employing h-BN as a platform material for large-area carbon electronics.

cond-mat.mtrl-sci↗

arXiv2011

Highly Conductive 3D Nano-Carbon: Stacked Multilayer Graphene System with Interlayer Decoupling

We investigate electrical conduction and breakdown behavior of 3D nano-carbon-stacked multilayer graphene (s-MLG) system with complete interlayer decoupling. The s-MLG is prepared by transferring and stacking large-area CVD-grown graphene monolayers, followed by wire patterning and plasma etching. Raman spectroscopy was used to confirm the layer number. The D-band peak indicates low defect level in the samples. Electrical current stressing induced doping is performed to shift the charge-neutrality Dirac point and decrease the graphene/metal contact resistance, improving the overall electrical conduction. Breakdown experiments show the current-carrying capacity of s-MLG is largely enhanced as compared with that of monolayer graphene.

cond-mat.mtrl-sci↗

arXiv2011

Local Electrical Stress-Induced Doping and Formation of 2D Monolayer Graphene P-N Junction

We demonstrated doping in 2D monolayer graphene via local electrical stressing. The doping, confirmed by the resistance-voltage transfer characteristics of the graphene system, is observed to continuously tunable from N-type to P-type as the electrical stressing level (voltage) increases. Two major physical mechanisms are proposed to interpret the observed phenomena: modifications of surface chemistry for N-type doping (at low-level stressing) and thermally-activated charge transfer from graphene to SiO2 substrate for P-type doping (at high-level stressing). The formation of P-N junction on 2D graphene monolayer is demonstrated with complementary doping based on locally applied electrical stressing.

cond-mat.mtrl-sci↗