Metallic Micro/Nanoscale Structures And Its Optoelectronic Engineering In ZnTe Nano Wires

Thanks to the unique one-dimensional structure and tunable optoelectronic properties,semiconductor nanowires have opened new avenues in photonics and solar energy harvesting,and provided an extraordinary platform for nano-optoelectronic applications,including photodetectors,solar cells,lasers,and nonlinear photonic devices.On the other hand,with the rapid development of micro/nano fabrication technologies,metallic micro/nano-scaled structures can be implemented into optoelectronic devices.Owing to the sub-wavelength scale near field enhancement induced by surface plasmon,the photonic properties can be effectively modulated and as a result,it is expected to achieve high performance in highly integrated optoelectronic devices.The research framework of this thesis is focusing on the fundamental research on the plasmonic phenomena in metal/nanowire hybrid structures,including absoption efficiency,polarization anisotropy,radiative emission enhancement,and their modulation effect on the nonlinear optical properties of ZnTe:O nanowires.The main research accomplishments are included as follows:1.The zincblende ZnTe nanowires were grown by chemical vapor transport technique and careful oxidization process were performed to achieve high quality ZnTe:O/ZnO core-shell structured nano wires with aspect ratio from 100 to 1000.The single nanowire exhibits strong near-band edge emission and broad band emission related to intermediate band states induced by isoelectronic oxygen doping in the gap at room temperature.Furthermore,the observation of multiple LO phonon overtones indicates high crystalline quality of nanowire and strong interaction of LO phonons and electrons or excitons in such polar semiconductor.2.The manipulation of absorption efficiency from ZnTe:O/ZnO core-shell nanowire coupled with A1 plasmonic bowtie antenna array was investigated.The nanowire/plamson coupling structure was optimized and fabricated to solve the low absorption of intermediate band of ZnTe:O/ZnO nanowires.The strong coupling of dielectric resonance in ZnTe:O nanowire with the localized surface plasmon resonance induced by the A1 bowtie antenna array leads to multiband absorption efficiency enhancement,especially for intermediate band,which effectively improve the capability of sub-gap photon absorption and pave an alternative way to realize high efficiency solar cells.3.Modulation of polarization response and quantum efficiency of ZnTe nanowires by Al bowtie antenna has been studied.The absorption and emission of bare nanowire exhibit very serious anisotropic polarization response,while the integrated bowtie antenna improved the emission efficiency and suppressed the anisotropic polarization response under transverse polarized light excitation.It is attributed to the enhancement of local field and spontaneous radiation rate induced by the strong coupling of localized surface plasmon in Al bowtie antenna.The coupling of A1 bowtie antenna improve the quantum efficiency of emissions greatly especially for low efficient emitters.4.Improvement of nonlinear energy transfer process in ZnTe nanowires was realized by coating randomly distributed Ag nanoparticles.The theoretical calculation indicates that the dimension of ZnTe/ZnO nanowires and the coated Ag nanoparticles have profound effect on the efficiency of fundamental and second harmonic generation.The surface enhanced Raman and nonlinear energy transfer process has been demonstrated in experiment and exhibit excellent agreement with the simulation results.As the Ag plasmonic resonant wavelength matching the second harmonic generation,the efficiency of nonlinear transfer process in Ag/ZnTe nanowire system was boosted 12.5 times as compared to the bare nanowire.