The Study On Hot Electrons In Metal-Semiconductor Composite Structures

In recent years,hot electrons generated by surface plasmon resonance nonradiative dumping can be injected into semiconductor conduction bands,which can improve the efficiency of traditional semiconductor devices.It has broad application prospects in the fields of photovoltaic,photocatalytic and photoelectric detection,thus becoming a research hotspot of plasmon photonics.In this paper,we focus on the generation,transfer and control of hot electrons induced by surface plasmon in metal-semiconductor composite films.By adjusting the linewidth,resonance position and intensity,polarization and angle dependence of plasmon,it is realized that photoelectric response characteristics are tailored by changing the wavelength and polarization.Meanwhile,the application in image sensing and photoelectric detection is explored.The main research work of this paper is divided into the following two parts:(1)The fabrication of bimetal-titania nanotube composite films and the study of their photoelectric propertiesLarge-aperture and highly ordered TiO2 nanotubes were prepared by atomic layer deposition using AAO as template,and loaded with different amounts of Au,Al and Au/Al nanoparticles,respectively.The results show that the photocurrent of TiO2 nano tubes loaded with Au nanoparticles increases significantly under visible light irradiation compared with pure TiO2 nanotubes.The photocurrent of samples increases by 400%under 568nm irradiation.The photocurrent of TiO2 nanotubes loaded with Al nanoparticles increases significantly under ultraviolet light irradiation,and the photocurrent of samples increases by 50%under 365nm irradiation.The photocurrent in the whole ultraviolet-visible-near infrared region of the nanotubes was significantly enhanced.The remarkable increase in photocurrent is attributed to the enhanced optical absorption of surface plasmons and the injection of hot electrons induced by plasmons.(2)The fabrication of double-plasmon composite films and the study of their photoelectric propertiesMetal-semiconductor composite films with double plasmon structure were prepared by thermal annealing,PS sphere mask and etching technology,and their photocurrent properties were studied.The results show that the plasmon resonance positions of the upper and lower metal micro-nanostructures are different.In the short wavelength region,the plasmon resonance of the top metal micro-nanostructures is stimulated,and in the long wavelength region,the plasmon resonance of the metal micro-nanostructures is stimulated.Hot electrons induced by plasmon are transferred from metal to semiconductor.Therefore,the polarity of photocurrent measured in different wavelength ranges is different and the polarity of photocurrent is regulated.In addition,the optical voltage and photocurrent can be effectively regulated in the visible-near infrared spectrum by applying different bias voltages at both ends of the composite film.