Depositing Nanostructure Of Colloidal Quantum Dots By Using Atomic Force Mircroscope

Quantum dots and their composed complex nanostructures have many advantages such as well optical properties,adjustable energy band structure,which have been widely used in many fields of biomedicine,solar cells,lasers and LED display technologies.However,because of the large specific surface area,it is easy to be oxidized and reunited by the external environment,which greatly hinders its application.In order to solve this problem,an effective method is the package of organic molecules to make them stable,which provides a new idea for using quantum to construct nanodevices.The Atomic Force Microscope(AFM)has become an indispensable tool in the field of nanotechnology research because of its high resolution,simple operation and ability of working in atmospheric,vacuum and liquid environments.Quantum dot array structures based on AFM assisted technology generally have small defects and high quality.In this paper,a well-distributed ordered colloidal CdSe quantum dot array structure was prepared by AFM mechanical lithography technique combined with optically induced electrochemical deposition.The main research work is as followed:1.The colloidal CdSe quantum dots with oleic acid molecular coating on the surface were prepared by colloidal chemical method.The CdSe quantum dot we prepared was a zinc blende nanostructures,and was existed in the form of colloidal clusters in n-hexane solution,with good mondispersion and uniform size,which can be combined with other positively charged ions.Such characteristics made it as a reliable raw material for the fabrication of nanostructures by electrochemical deposition methods.2.According to the basic principle of AFM mechanical lithography,the nano-hole structure was constructed on the surface of aluminum film.The effect of applied tip force,scratching speed and the cycle number of scratch on the morphology and depth of the nano-hole was analyzed,the optimal scratching parameters with a loading force of 7.36mN,scratching speed of 4mm/s and cycle number of 6 times were obtained.Finally,a nano-hole array of aluminumwith uniform distribution was obtained by using the parameter.3.The CdSe quantum dots with carboxyl groups on the surface were induced to deposit on the aluminum nano-hole array substrates by picosecond laser induced electrochemical deposition(OIED)method,and formed ordered CdSe quantum dot array nanostructures in the end;And then the morphology and fluorescence studies were performed in situ using a scanning near-field optical microscope(SNOM).The results showed that a colloidal CdSe array structure with uniform order and its stable fluorescence spectrum were obtained on the aluminum substrates.The results of this study could be provided a basis for new type of sensor with high precision,detectors,photovoltaics,photocatalysis,etc.