ZnSe nanoribbons were synthesized with chemical vapor deposition route. The excitation power-dependent photol and surface photovoltage （SPV） techniques were used to study the optoelectronic properties of the as-grow...ZnSe nanoribbons were synthesized with chemical vapor deposition route. The excitation power-dependent photol and surface photovoltage （SPV） techniques were used to study the optoelectronic properties of the as-grown ZnSe nanoribbons. Three deep defect （DD）-related emission bands, respectively, centered at 623 nm （DD1）, 563 nm （DD2） and 525 nm （DD3）, emerge orderly with increasing the excitation power, which is attributed to the saturation of the DD states from deeper to shallower level. The SPV spectrum and the corresponding phase spectrum show that DD1 mainly acts as recombination center, while DD2 and DD3 can act as both the recombination center and electron traps. The influence of the trapping electrons on the SPV response dynamic was studied with transient SPV.展开更多
There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining l...There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining large area thin films of MoS2 for future device applications still remains a challenge. In the present study, the amounts of the precursors （S and MOO3） were varied systematically in order to optimize the growth of highly crystalline and large area MoS2 layers by the chemical vapor deposition method. Careful control of the amounts of precursors was found to the key factor in the synthesis of large area highly crystalline flakes. The thickness of the layers was confirmed by Raman spectroscopy and atomic force microscopy. The optical properties and chemical composition were studied by photoluminescence （PL） and X-ray photoelectron spectroscopy. The emergence of strong direct excitonic emissions at 1.82 eV （A-exciton, with a normalized PL intensity of -55 × 10^3） and 1.98 eV （B-exciton, with a normalized PL intensity of -5 × 10^3） of the sample at room temperature clearly indicates the high luminescence quantum efficiency. The mobility of the films was found to be 0.09 cm^2/（V.s） at room temperature. This study provides a method for the controlled synthesis of high-quality two-dimensional （2D） transition metal dichalcogenide materials, useful for applications in nanodevices, optoelectronics and solar energv conversion.展开更多
The photoluminescence(PL) properties of porous silicon microcavities(PSMs) in the visible range at room temperature are improved by doping the rare earth ytterbium(Yb) into PSMs prepared by the electrochemical etching...The photoluminescence(PL) properties of porous silicon microcavities(PSMs) in the visible range at room temperature are improved by doping the rare earth ytterbium(Yb) into PSMs prepared by the electrochemical etching method.It is observed that PSMs doped with the rare earth have an emission band around 630 nm.Compared with the single-layer porous silicon(PS) film,the PSMs doped with Yb have narrower and stronger PL spectrum.展开更多
基金supported by the National Natural Science Foundation of China(11374092,61474040,11204073)the National Basic Research Program of China(2012CB933703)the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province and the Hunan Provincial Science and Technology Department(2014FJ2001,2014GK3015,2014TT1004)
文摘ZnSe nanoribbons were synthesized with chemical vapor deposition route. The excitation power-dependent photol and surface photovoltage （SPV） techniques were used to study the optoelectronic properties of the as-grown ZnSe nanoribbons. Three deep defect （DD）-related emission bands, respectively, centered at 623 nm （DD1）, 563 nm （DD2） and 525 nm （DD3）, emerge orderly with increasing the excitation power, which is attributed to the saturation of the DD states from deeper to shallower level. The SPV spectrum and the corresponding phase spectrum show that DD1 mainly acts as recombination center, while DD2 and DD3 can act as both the recombination center and electron traps. The influence of the trapping electrons on the SPV response dynamic was studied with transient SPV.
文摘There has been growing research interest in the use of molybdenum disulfide in the fields of optoelectronics and energy harvesting devices, by virtue of its indirect-to-direct band gap tunability. However, obtaining large area thin films of MoS2 for future device applications still remains a challenge. In the present study, the amounts of the precursors （S and MOO3） were varied systematically in order to optimize the growth of highly crystalline and large area MoS2 layers by the chemical vapor deposition method. Careful control of the amounts of precursors was found to the key factor in the synthesis of large area highly crystalline flakes. The thickness of the layers was confirmed by Raman spectroscopy and atomic force microscopy. The optical properties and chemical composition were studied by photoluminescence （PL） and X-ray photoelectron spectroscopy. The emergence of strong direct excitonic emissions at 1.82 eV （A-exciton, with a normalized PL intensity of -55 × 10^3） and 1.98 eV （B-exciton, with a normalized PL intensity of -5 × 10^3） of the sample at room temperature clearly indicates the high luminescence quantum efficiency. The mobility of the films was found to be 0.09 cm^2/（V.s） at room temperature. This study provides a method for the controlled synthesis of high-quality two-dimensional （2D） transition metal dichalcogenide materials, useful for applications in nanodevices, optoelectronics and solar energv conversion.
基金supported by the National Natural Science Foundation of China(Nos.61575168 and 61265009)the Xinjiang Science and Technology Project(No.201412112)
文摘The photoluminescence(PL) properties of porous silicon microcavities(PSMs) in the visible range at room temperature are improved by doping the rare earth ytterbium(Yb) into PSMs prepared by the electrochemical etching method.It is observed that PSMs doped with the rare earth have an emission band around 630 nm.Compared with the single-layer porous silicon(PS) film,the PSMs doped with Yb have narrower and stronger PL spectrum.
