arXiv subjects

Dan Guo

Publications and source records attributed to Dan Guo.

112 records · Page 7Linked to original sources

arXiv2019

A strain tunable single-layer MoS2 photodetector

Strain engineering, which aims to tune the bandgap of a semiconductor by the application of strain, has emerged as an interesting way to control the electrical and optical properties of two-dimensional (2D) materials. Apart from the changes in the intrinsic properties of 2D materials, the application of strain can be also used to modify the characteristics of devices based on them. In this work, we study flexible and transparent photodetectors based on single-layer MoS2 under the application of biaxial strain. We find that by controlling the level of strain, we can tune the photoresponsivity (by 2-3 orders of magnitude), the response time (from <80 ms to 1.5 s) and the spectral bandwidth (with a gauge factor of 135 meV/% or 58 nm/%) of the device.

physics.app-ph↗

arXiv2019

Study of Unflavored Light Mesons with $J^{PC}=2^{--}$

The unflavored light meson families, namely $ω_2$, $ρ_2$, and $ϕ_2$, are studied systematically by investigating the spectrum and the two-body strong decays allowed by Okubo-Zweig-Iizuka rule. Including the four experimentally observed states and other predicted states, phenomenological analysis of the partial decay widths can verify the corresponding assignments of these states into the families. Moreover, we provide typical branching ratios of the dominant decay channels, especially for missing ground states, which is helpful to search for or confirm them and explore more properties of these families at experiment.

hep-ph↗

arXiv2018

Calculations of point defects in the layered MX2 (M=Mo, W; X=S, Te): Substitution by the groups III, V and VII elements

Dopability in semiconductors plays a crucial role in device performance. Using the first-principles density-functional theory calculations, we investigate systematically the doping properties of layered MX2 (M= Mo, W; X=S, Te) by replacing M or X with the groups III, V and VII elements. It is found that the defect BM is hard to form in MX2 due to the large formation energy originating from the crystal distortion, while AlM is easy to realize compared to the former. In MoS2, WS2 and MoTe2, Al is the most desirable p-type dopant under anion-rich conditions among the group III components, since AlM has relatively low transition and formation energies. With respect to the doping of the group V elements, it is found that the substitutions on the cation sites have deeper defect levels than those on the anion sites due to the strong electronegativity. AsTe and SbTe in MoTe2 and WTe2 are trend to form shallow acceptors under cation-rich conditions, indicating high hole-concentrations for p-type doping, whereas SbS in MoS2 and PTe in WTe2 are shown to be good p-type candidates under cation-rich conditions. In despite of that the substitutions of group VII on X site have low formation energies, the transition energies are too high to achieve n-type MoS2 and WS2. Nevertheless, for MoTe2, the substitutions with the group VII elements on the anion sites are suitable for n-type doping on account of the shallow donor levels and low formation energies under Mo-rich condition. As to WTe2, F is the only potential donor due to the shallow transition energy of FTe. Our findings of filtering out unfavorable and identifying favorable dopants in MX2 are very valuable for experimental implementations.

cond-mat.mtrl-sci↗

arXiv2011

Extremal incomplete sets in finite abelian groups

Let $G$ be a finite abelian group. The critical number ${\rm cr}(G)$ of $G$ is the least positive integer $\ell$ such that every subset $A\subseteq G\setminus\{0\}$ of cardinality at least $\ell$ spans $G$, i.e., every element of $G$ can be written as a nonempty sum of distinct elements of $A$. The exact values of the critical number have been completely determined recently for all finite abelian groups. The structure of these sets of cardinality ${\rm cr}(G)-1$ which fail to span $G$ has also been characterized except for the case that $|G|$ is an even number and the case that $|G|=pq$ with $p,q$ are primes. In this paper, we characterize these extremal subsets for $|G|\geq 36$ is an even number, or $|G|=pq$ with $p,q$ are primes and $q\geq 2p+3$.

math.CO↗