The electrical performance of two-dimensional transition metal dichalcogenides （TMDs） is strongly affected by the number of structural defects. In this work, we provide an optical spectroscopic characterization appr...The electrical performance of two-dimensional transition metal dichalcogenides （TMDs） is strongly affected by the number of structural defects. In this work, we provide an optical spectroscopic characterization approach to correlate the number of structural defects and the electrical performance of WSe2 devices. Low-temperature photoluminescence （PL） spectra of electron-beam-lithography- processed WSe2 exhibit a clear defect-induced PL emission due to excitons bound to defects, which would strongly degrade the electrical performance. By adopting an electron-beam-free transfer-electrode technique, we successfully prepared a backgated WSe2 device containing a limited amount of defects. A maximum hole mobility of approximately 200 cm2.V -1.s-1 was achieved because of the reduced scattering sources, which is the highest reported value for this type of device. This work provides not only a versatile and nondestructive method to monitor the defects in TMDs but also a new route to approach the room-temperature phonon-limited mobility in high-performance TMD devices.展开更多
CVD graphene is a promising candidate for optoelectronic applications due to its high quality and high yield.However,multi-layer domains could inevitably form at the nucleation centers during the growth.Here,we propos...CVD graphene is a promising candidate for optoelectronic applications due to its high quality and high yield.However,multi-layer domains could inevitably form at the nucleation centers during the growth.Here,we propose an optical imaging technique to precisely identify the multilayer domains and also the ratio of their coverage in large-scale CVD monolayer graphene.We have also shown that the stacking disorder in twisted bilayer graphene as well as the impurities on the graphene surface could be distinguished by optical imaging.Finally,we investigated the effects of bilayer domains on the optical and electrical properties of CVD graphene,and found that the carrier mobility of CVD graphene is seriously limited by scattering from bilayer domains.Our results could be useful for guiding future optoelectronic applications of large-scale CVD graphene.展开更多
基金This work was supported by National Natural Science Foundation of China （Nos. 61422503, 21541013 and 61376104）, Natural Science Foundation of Jiangsu Province （No. BK20150596）, Jiangsu key laboratory for advanced metallic materials （No. BM2007204）, the open research funds of Key Laboratory of MEMS of Ministry of Education （SEU, China）, and the Funda- mental Research Funds for the Central Universities. The authors would like to thank Prof. Zhenhua Qiao from USTC, China for helpful discussions.
文摘The electrical performance of two-dimensional transition metal dichalcogenides （TMDs） is strongly affected by the number of structural defects. In this work, we provide an optical spectroscopic characterization approach to correlate the number of structural defects and the electrical performance of WSe2 devices. Low-temperature photoluminescence （PL） spectra of electron-beam-lithography- processed WSe2 exhibit a clear defect-induced PL emission due to excitons bound to defects, which would strongly degrade the electrical performance. By adopting an electron-beam-free transfer-electrode technique, we successfully prepared a backgated WSe2 device containing a limited amount of defects. A maximum hole mobility of approximately 200 cm2.V -1.s-1 was achieved because of the reduced scattering sources, which is the highest reported value for this type of device. This work provides not only a versatile and nondestructive method to monitor the defects in TMDs but also a new route to approach the room-temperature phonon-limited mobility in high-performance TMD devices.
基金Project supported by the National Natural Science Foundation of China(Nos.61422503,61376104)the Open Research Funds of Key Laboratory of MEMS of Ministry of Education(SEU,China)the Fundamental Research Funds for the Central Universities
文摘CVD graphene is a promising candidate for optoelectronic applications due to its high quality and high yield.However,multi-layer domains could inevitably form at the nucleation centers during the growth.Here,we propose an optical imaging technique to precisely identify the multilayer domains and also the ratio of their coverage in large-scale CVD monolayer graphene.We have also shown that the stacking disorder in twisted bilayer graphene as well as the impurities on the graphene surface could be distinguished by optical imaging.Finally,we investigated the effects of bilayer domains on the optical and electrical properties of CVD graphene,and found that the carrier mobility of CVD graphene is seriously limited by scattering from bilayer domains.Our results could be useful for guiding future optoelectronic applications of large-scale CVD graphene.
