Islam A S M Jannatul, Islam Md Sherajul, Islam Md Rasidul, Stampfl Catherine, Park Jeongwon
Department of Electrical and Electronic Engineering, Khulna University of Engineering & Technology, Khulna 9203, Bangladesh.
Department of Electrical and Biomedical Engineering, University of Nevada, Reno, NV 89557, United States of America.
Nanotechnology. 2021 Aug 2;32(43). doi: 10.1088/1361-6528/ac12ec.
Of late, atomically thin two-dimensional zinc-sulfide (2D-ZnS) shows great potential for advanced nanodevices and as a substitute to graphene and transition metal di-chalcogenides owing to its exceptional optical and electronic properties. However, the functional performance of nanodevices significantly depends on the effective heat management of the system. In this paper, we explored the thermal transport properties of 2D-ZnS through molecular dynamics simulations. The impact of length, temperature, and vacancy defects on the thermal properties of 2D-ZnS are systematically investigated. We found that the thermal conductivity (TC) rises monotonically with increasing sheet length, and the bulk TC of ∼30.67 W mKis explored for an infinite length ZnS. Beyond room temperature (300 K), the TC differs from the usual 1/rule and displays an abnormal, slowly declining behavior. The point vacancy (PV) shows the largest decrease in TC compared to the bi vacancy (BV) defects. We calculated phonon modes for various lengths, temperatures, and vacancies to elucidate the TC variation. Conversely, quantum corrections are used to avoid phonon modes' icing effects on the TC at low temperatures. The obtained phonon density of states (PDOS) shows a softening and shrinking nature with increasing temperature, which is responsible for the anomaly in the TC at high temperatures. Owing to the increase of vacancy concentration, the PDOS peaks exhibit a decrease for both types of defects. Moreover, the variation of the specific heat capacity and entropy with BV and PV signify our findings of 2D-ZnS TC at diverse concentrations along with the different forms of vacancies. The results elucidated in this study will be a guide for efficient heat management of ZnS-based optoelectronic and nano-electronic devices.
近来，原子级薄的二维硫化锌（2D-ZnS）因其优异的光学和电子特性，在先进纳米器件领域展现出巨大潜力，有望替代石墨烯和过渡金属二硫属化物。然而，纳米器件的功能性能很大程度上取决于系统的有效热管理。在本文中，我们通过分子动力学模拟探究了2D-ZnS的热输运特性。系统研究了长度、温度和空位缺陷对2D-ZnS热性能的影响。我们发现，热导率（TC）随片长增加而单调上升，对于无限长的ZnS，其体热导率约为30.67 W/(m·K)。超过室温（300 K）后，热导率不同于通常的1/T规律，呈现异常的缓慢下降行为。与双空位（BV）缺陷相比，单空位（PV）导致的热导率下降幅度最大。我们计算了不同长度、温度和空位情况下的声子模式，以阐明热导率的变化。相反，采用量子修正来避免低温下声子模式对热导率的冻结效应。所得到的声子态密度（PDOS）随温度升高呈现软化和收缩特性，这是高温下热导率出现异常的原因。由于空位浓度增加，两种类型缺陷的PDOS峰均出现下降。此外，比热和熵随BV和PV的变化表明了我们在不同浓度以及不同空位形式下对2D-ZnS热导率的研究结果。本研究阐明结果将为基于ZnS的光电器件和纳米电子器件的高效热管理提供指导。
