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Preparation And Photoluminescence Study Of One-dimensional ZnTe/ZnSe Nanostructures

Posted on:2014-06-17Degree:MasterType:Thesis
Country:ChinaCandidate:J J GuoFull Text:PDF
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One-dimensional (1-D) and quasi1-D semiconductor nanostructures, such asnanowires (NWs), nanorods and nanotubes, have attracted much attention due totheir potential applications as building blocks for nanoscale transistors, sensorsand optoelectronic devices. The one-dimensional ZnTe/ZnSe semiconductornanomaterials, including ZnTe single crystalline nanowires, twinning nanobelts,nano-leaves, nanowire arrays, nano-trees, nano-flowers, are synthesized bychemical vapor deposition method in this thesis. The structural features anddifferences between the ZnTe single crystalline nanowires and twinning nanobeltsare discussed in detail. The formation mechanism of twin structures in ZnTenanobelts is studied. The ZnTe nanowires shows a high purity with length of up toseveral hundreds microns. Alternating twins are occurred in ZnTe nanobelts withgrowth direction along the [111]. The power-dependent PL detection is used tostudy the optical properties of these ZnTe nanostructures. The emission intensityincreases with increasing the excitation intensity. Both the structures havesignificant power-dependent redshift of PL emission peak, with the redshiftmagnitude of the NBs larger than that of the NWs. A careful investigation for thespectra redshift reveals the redshift magnitude is highly related to the structures.The redshift of PL spectra from ZnTe NWs is mainly attributed to the band-gaprenormalization effect. Furthermore, the electron-hole plasma effect may intensifythe spectra redshift of twinning NBs. It is expected that the ZnTe nanostructureswill be applied in nanodevice designation due to their optical property. In addition,ZnSe nanowires and nanobelts are synthesized by a simple chemical vapordeposition method. The experiment shows that the synthesized ZnSe nanowiresand nanobelts are single crystalline blende structure. Photoluminescenceproperties of ZnSe nanowires and nanobelts are studied at room temperature.Power-dependent redshift of PL emission peak is observed in the both ZnSenanowires and nanobelts with increasing the excitation power. The PL redshift isattributed to the band-gap renormalization effect due to the increased carrierdensity and carrier interactions. The behavior of the optical waveguide of ZnSenanowires and nanobelts has been carefully studied. The experiment shows theemission spectrum redshifts with12nm in the process of optical waveguide. This is due to several interband radiative recombination processes occur when thephotons propagate in the ZnSe nanowires and nanobelts cavity which lead toenergy losses. That is, the redshift of the emission spectrum is caused byself-absorption effect. This character may be applied in the laser emission, opticalwaveguide and micro-and nano-scale photonic devices...
Keywords/Search Tags:One dimensional Semiconductor Nanostructures, Chemical Vapor Deposition, Twin Structure, Photoluminescence, Redshift, Optical Waveguide, ZnTe, ZnSe
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