arXiv subjects

Kui Gong

Publications and source records attributed to Kui Gong.

3 recordsLinked to original sources

arXiv2018

High intrinsic $ZT$ in InP$_3$ monolayer at room temperature

Two-dimensional thermoelectric materials with a figure of merit $ZT$, which is greater than 2.0 at room temperature, would be highly desirable in energy conversion since the efficiency is competitive to conventional energy conversion techniques. Here, we propose that the indium triphosphide (InP$_3$) monolayer offers an extraordinary $ZT$ of 2.2 at 300 K by using quantum calculations within the ballistic thermal transport region. A remarkably low and isotropic phononic thermal conductivity is founded, which is due to flat lattice vibration modes. This low thermal conductivity takes a major responsibility to the impressively high $ZT$. Moreover, a large $ZT$ that is greater than 1.5 can be maintained, even if a 1% mechanic extension is applied on the lattice. These results suggest that the InP$_3$ monolayer is a promising candidate for low dimensional thermoelectric applications.

cond-mat.mtrl-sci↗

arXiv2014

Electrical contacts to monolayer black Phosphorus: a first principles investigation

We report first principles theoretical investigations of possible metal contacts to monolayer black phosphorus (BP). By analyzing lattice geometry, five metal surfaces are found to have minimal lattice mismatch with BP: Cu(111), Zn(0001), In(110), Ta(110) and Nb(110). Further studies indicate Ta and Nb bond strongly with monolayer BP causing substantial bond distortions, but the combined Ta-BP and Nb-BP form good metal surfaces to contact a second layer BP. By analyzing the geometry, bonding, electronic structure, charge transfer, potential and band bending, it is concluded that Cu(111) is the best candidate to form excellent Ohmic contact to monolayer BP. Other four metal surfaces or combined surfaces also provide viable structures to form metal/BP contacts, but they have Schottky character.

cond-mat.mes-hall↗

arXiv2013

Electric control of spin in monolayer WSe2 field effect transistors

We report a first principles theoretical investigation of quantum transport in monolayer WSe2 field effect transistor (FET). Due to a strong spin-orbit interaction (SOI) and the atomic structure of the two-dimensional (2D) lattice, monolayer WSe2 has an interesting electronic structure that exhibits Zeeman-like up-down spin texture near the K and K' points of the Brillouin zone. In a FET, the gate electric field induces an extra, externally tunable SOI that re-orients the spins into a Rashba-like texture thereby realizing electric control of the spin. Quantum transport is modulated by the spin texture, namely by if the spin orientation of the carrier after the gated channel region, matches or miss-matches that of the FET drain electrode. The carrier current in the FET is labelled both the spin index and the valley index, realizing spintronics and valleytronics in the same device.

cond-mat.mes-hall↗