运用密度泛函理论的第一性原理方法,研究了本征和不同浓度Nb掺杂单层MoS_2的晶体几何结构、能带结构、态密度、电荷局域密度函数以及形成能。计算结果发现,本征单层MoS_2为直接带隙,禁带宽度为1.67 e V。随着Nb掺杂浓度的增加,单层MoS_...运用密度泛函理论的第一性原理方法,研究了本征和不同浓度Nb掺杂单层MoS_2的晶体几何结构、能带结构、态密度、电荷局域密度函数以及形成能。计算结果发现,本征单层MoS_2为直接带隙,禁带宽度为1.67 e V。随着Nb掺杂浓度的增加,单层MoS_2价带顶会越过费米能级向高能区方向移动,导带底则向低能区方向移动,致使其禁带宽度大幅度减小。当掺杂浓度为8.33%时,其禁带宽度减小至1.30 e V。带隙值的大幅减小,电子从价带激发到导带变得更容易,应用在以晶体管为代表的逻辑器件等领域,将使其电流开关比、导电性等电学性能得到显著提升。此外,掺杂前后成键类型均是离子键与共价键的混合键,形成能较低,说明掺杂体系的热力学稳定性良好,易于实现。研究结果为单层MoS_2在半导体器件的实际应用提供了理论指导。展开更多
A novel and facile oxidation-induced self-doping process of graphene-silicon Schottky junction by nitric acid（HNO3） vapor is reported. The HNO3 oxidation process makes graphene p-type self-doped, and leads to a high...A novel and facile oxidation-induced self-doping process of graphene-silicon Schottky junction by nitric acid（HNO3） vapor is reported. The HNO3 oxidation process makes graphene p-type self-doped, and leads to a higher built-in potential and conductivity to enhance charge transfer and to suppress charge carrier recombination at the graphene-silicon Schottky junction. After the HNO3 oxidation process, the open-circuit voltage is increased from the initial value of 0.36 V to the maximum value of 0.47 V, the short-circuit current is greatly increased from 0.80μA to 7.71μA, and the ideality factor is optimized from 4.4 to 1.0. The enhancement of the performance of graphene-Si solar cells may be due to oxidation-induced p-type self-doping of graphene-Si junctions.展开更多
文摘运用密度泛函理论的第一性原理方法,研究了本征和不同浓度Nb掺杂单层MoS_2的晶体几何结构、能带结构、态密度、电荷局域密度函数以及形成能。计算结果发现,本征单层MoS_2为直接带隙,禁带宽度为1.67 e V。随着Nb掺杂浓度的增加,单层MoS_2价带顶会越过费米能级向高能区方向移动,导带底则向低能区方向移动,致使其禁带宽度大幅度减小。当掺杂浓度为8.33%时,其禁带宽度减小至1.30 e V。带隙值的大幅减小,电子从价带激发到导带变得更容易,应用在以晶体管为代表的逻辑器件等领域,将使其电流开关比、导电性等电学性能得到显著提升。此外,掺杂前后成键类型均是离子键与共价键的混合键,形成能较低,说明掺杂体系的热力学稳定性良好,易于实现。研究结果为单层MoS_2在半导体器件的实际应用提供了理论指导。
基金Supported by the National Natural Science Foundation of China under Grant Nos 61504113,61674113 and 51622507the Natural Science Foundation of Shanxi Province under Grant No 2016011040+1 种基金the Natural Science Foundation of Fujian Province under Grant No 2018J01567the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi Province under Grant No 2016138
文摘A novel and facile oxidation-induced self-doping process of graphene-silicon Schottky junction by nitric acid（HNO3） vapor is reported. The HNO3 oxidation process makes graphene p-type self-doped, and leads to a higher built-in potential and conductivity to enhance charge transfer and to suppress charge carrier recombination at the graphene-silicon Schottky junction. After the HNO3 oxidation process, the open-circuit voltage is increased from the initial value of 0.36 V to the maximum value of 0.47 V, the short-circuit current is greatly increased from 0.80μA to 7.71μA, and the ideality factor is optimized from 4.4 to 1.0. The enhancement of the performance of graphene-Si solar cells may be due to oxidation-induced p-type self-doping of graphene-Si junctions.
基金supported by the National Natural Science Foundation of China (U21A20496,61922060,62205235,62204157,61805172,12104334,62174117,and 61905173)the Graduate Innovation Project of Shanxi Province (2020BY117)+9 种基金the Key Research and Development (International Cooperation)Program of Shanxi Province (201803D421044)the Natural Science Foundation of Shanxi Province (20210302123154 and 20210302123169)Research Project Supported by Shanxi Scholarship Council of China (2021-033)Research Project Supported by Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering (2021SX-FR008 and 2022SX-TD020)Introduction of Talents Special Project of Lvliang City (Rc2020206,Rc2020207)Transformation Cultivation Project of University Scientific and Technological Achievements of Shanxi Province (2020CG013)the Key Research and Development Program of Shanxi Province (202102150101007)the support from the Research Grants Council,University Grants Committee,Hong Kong,General Research Fund (12303920)SZ-HK-Macao Science and Technology Plan Project (SGDX2020110309540000)Guangdong Basic and Applied Basic Research Fund (2022A1515010020)。
