A unique needlelike sandwich structure is observed in the P3HT：PCBM blend films after annealing at 220℃. The real-time observation of a growing needle indicates that the needle exhibits 7μm/rain longitudinal growth...A unique needlelike sandwich structure is observed in the P3HT：PCBM blend films after annealing at 220℃. The real-time observation of a growing needle indicates that the needle exhibits 7μm/rain longitudinal growth rate and no lateral growth. Both confocal fluorescence and Raman microscopic mapping measurements reveal that these needles have a PCBM core sandwiched between P3HT edges. According to the eutectic nature of P3HT：PCBM nature, when annealing at high temperature （-220℃）, the aggregation of PCBM results in recxTstallization of P3HT in the PCBM-depleted regions. These results will give dearer understanding of the melting, diffusion, and recrystallization behavior of the organic eutectic system.展开更多
GaAs nanowires are synthesized on fused quartz substrates by using molecular beam epitaxy via a vapor-liquidsolid mechanism with gold as the catalyst. High resolution-transmission electron microscopy is used to probe ...GaAs nanowires are synthesized on fused quartz substrates by using molecular beam epitaxy via a vapor-liquidsolid mechanism with gold as the catalyst. High resolution-transmission electron microscopy is used to probe crystal quality and growth direction. Miero-photolumineseenee measurements are carried out to examine the optical properties of GaAs NWs. The low-temperature photoluminescenee （PL） emission of nanowires （NWs） has a peak at 1.513eV, 2meV lower than the zinc blende GaAs free exciton energy. The temperature-dependent band gap of NWs is seen to be somewhat different from that observed in bulk OaAs, and the PL rapidly quenches above 150K, with an activation energy of 6.3meV reflecting the presence of the longitudinal twins＇ structure.展开更多
The growth of GaAs nanowires directly on fused quartz substrates using molecular beam epitaxy via a vapor-liquid-solid mechanism with gold as catalyst is reported. Unlike conventional Au-catalyst MBE growth of nanowir...The growth of GaAs nanowires directly on fused quartz substrates using molecular beam epitaxy via a vapor-liquid-solid mechanism with gold as catalyst is reported. Unlike conventional Au-catalyst MBE growth of nanowires （NWs） on GaAs substrates, zinc blende is found to be the dominant crystal structure for NWs grown on fused-quartz substrates by MBE. Further transmission electron microscopy measurements show that the prepared ZB NWs have the growth direction of [112] and lamellar { 111 } twins extend through the length of NWs. Although there are longitudinal planar defects that extend through NWs, the narrow full width at half maximum of PL implies high crystal quality of NWs grown on fused-quartz substrates.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 11104271 and 11179042.
文摘A unique needlelike sandwich structure is observed in the P3HT：PCBM blend films after annealing at 220℃. The real-time observation of a growing needle indicates that the needle exhibits 7μm/rain longitudinal growth rate and no lateral growth. Both confocal fluorescence and Raman microscopic mapping measurements reveal that these needles have a PCBM core sandwiched between P3HT edges. According to the eutectic nature of P3HT：PCBM nature, when annealing at high temperature （-220℃）, the aggregation of PCBM results in recxTstallization of P3HT in the PCBM-depleted regions. These results will give dearer understanding of the melting, diffusion, and recrystallization behavior of the organic eutectic system.
文摘GaAs nanowires are synthesized on fused quartz substrates by using molecular beam epitaxy via a vapor-liquidsolid mechanism with gold as the catalyst. High resolution-transmission electron microscopy is used to probe crystal quality and growth direction. Miero-photolumineseenee measurements are carried out to examine the optical properties of GaAs NWs. The low-temperature photoluminescenee （PL） emission of nanowires （NWs） has a peak at 1.513eV, 2meV lower than the zinc blende GaAs free exciton energy. The temperature-dependent band gap of NWs is seen to be somewhat different from that observed in bulk OaAs, and the PL rapidly quenches above 150K, with an activation energy of 6.3meV reflecting the presence of the longitudinal twins＇ structure.
基金Project supported by the National Natural Science Foundation of China(Nos.11104271,11179042)
文摘The growth of GaAs nanowires directly on fused quartz substrates using molecular beam epitaxy via a vapor-liquid-solid mechanism with gold as catalyst is reported. Unlike conventional Au-catalyst MBE growth of nanowires （NWs） on GaAs substrates, zinc blende is found to be the dominant crystal structure for NWs grown on fused-quartz substrates by MBE. Further transmission electron microscopy measurements show that the prepared ZB NWs have the growth direction of [112] and lamellar { 111 } twins extend through the length of NWs. Although there are longitudinal planar defects that extend through NWs, the narrow full width at half maximum of PL implies high crystal quality of NWs grown on fused-quartz substrates.
