arXiv subjects

Kai-Tak Lam

Publications and source records attributed to Kai-Tak Lam.

3 recordsLinked to original sources

arXiv2014

Performance limits projection of black phosphorous field-effect transistors

Ballistic device performance of monolayer black phosphorous (BP) field-effect transistors (FET) is investigated in this work. Due to the anisotropic effect mass of the carriers, the ON-state current is dependent on the transport direction. The effective masses are lower in the "armchair" direction which provides higher drive current at the same biasing. The degree of anisotropy is higher for the holes, which improves the performance of p-type devices. The intrinsic delay of 20 nm BP FETs is in the range of 50 fs at ON-/OFF-current ratio of 4 orders. Monolayer BP FETs outperform both MoS$_2$ and Si FETs for both n- and p-type devices in terms of ballistic performance limits, due to highly anisotropic band structure.

cond-mat.mtrl-sci↗

arXiv2011

Ambipolar bistable switching effect of graphene

Reproducible current hysteresis is observed in graphene with a back gate structure in a two-terminal configuration. By applying a back gate bias to tune the Fermi level, an opposite sequence of switching with the different charge carriers, holes and electrons, is found. The charging and discharging effect is proposed to explain this ambipolar bistable hysteretic switching. To confirm this hypothesis, one-level transport model simulations including charging effect are performed and the results are consistent with our experimental data. Methods of improving the ON/OFF ratio of graphene resistive switching are suggested.

cond-mat.mes-hall↗

arXiv2008

An Ab Initio Study on Energy Gap of Bilayer Graphene Nanoribbons with Armchair Edges

Dependency of energy bandgap (Eg) of bilayer armchair graphene nanoribbons (AGNRB) on their widths, interlayer distance (D) and edge doping concentration of boron/nitrogen is investigated using local density approximation and compare to the results of monolayer graphene nanoribbons (AGNRM). Although Eg of AGNRB, in general, is smaller than that of AGNRM, AGNRB exhibits two distinct groups, metal and semiconductor, while AGNRM displays purely semiconducting behavior. Eg of AGNRB, moreover, is highly sensitive to D, indicating a possible application in tuning Eg by varying D. Finally, edge doping of both AGNR systems reduces Eg by 11-17%/4-10% for AGNRM/AGNRB, respectively.

cond-mat.mtrl-sci↗