Acta Chim. Sinica ›› 2015, Vol. 73 ›› Issue (9): 954-958.DOI: 10.6023/A15030220 Previous Articles     Next Articles

Special Issue: 非碳基二维材料



沈成a, 张菁a, 时东霞a, 张广宇a,b   

  1. a 中国科学院物理研究所 北京凝聚态物理国家实验室 北京 100190;
    b 量子物质科学协同创新中心 北京 100190
  • 投稿日期:2015-03-31 发布日期:2015-06-02
  • 通讯作者: 时东霞, 张广宇;
  • 基金资助:

    项目受科技部973项目(No. 2013CB934500)和国家自然科学基金(Nos. 61390503, 61325021, 91223204, 91323304)资助.

Photoluminescence Enhancement in Monolayer Molybdenum Disulfide by Annealing in Air

Shen Chenga, Zhang Jinga, Shi Dongxiaa, Zhang Guangyua,b   

  1. a Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190;
    b Collaborative Innovation Center of Quantum Matter, Beijing 100190
  • Received:2015-03-31 Published:2015-06-02
  • Supported by:

    Project supported by the National Basic Research Program of China (No. 2013CB934500) and the National Natural Science Foundation of China (Nos. 61390503, 61325021, 91223204, 91323304).

Monolayer molybdenum disulfide is a novel two-dimensional material beyond graphene. It is a direct band gap semiconductor with excellent electrical and optical properties, promising wide application in nanoelectronics and optoelectronics, thus has drawn much attention recently. In this paper, we investigate the enhancement of photoluminescence of monolayer molybdenum disulfide by annealing in air. Monolayer molybdenum disulfide samples were prepared by mechanical exfoliation and chemical vapor deposition with molybdenum oxide and sulfur as sources, and argon as carrier gas. We found that air annealing for several minutes can distinctly enhance the photoluminescence intensity of A exciton by an order of magnitude, which is much better than annealing in argon. The blue shift of A exciton peak is observed after air annealing for all the monolayer molybdenum disulfide samples prepared by different methods above. We also found that this phenomenon widely exists in samples with different substrates like silicon dioxide and sapphire. Electrical transport measurements were carried out and indicate that the carrier mobility of monolayer molybdenum disulfide is largely reduced after annealing in air, which might mean the formation of considerable defects. This phenomenon is believed to be due to the doping effect caused by adsorption of oxygen, which is bonded to the defects after annealing. As acceptors, these oxygen dopants change the distribution of trions and neutral excitons, resulting in less tritons but more neutral excitons. Neutral excitons yield much higher quantum efficiency. As a comparison, we carried out control experiments in which annealing was in NH3 atmosphere. We found that photoluminescence is red shifted and can be quenched. This research results give a simple and effective method to enhance the photoluminescence of monolayer molybdenum disulfide.

Key words: molybdenum disulfide, photoluminescence, exciton, charge transfer