Study On The Growth And Properties Of Silicon Phosphide 2-D Crystals By Chemical Vapor Transport

In recent years,the family of two-dimensional materials have been growing because of their novel properties,such as high transmittance,large specific surface area,high mobility of carriers and fast response rate.Silicon phosphide is a member of the IV-VA of new two-dimensional semiconductor materials,which has attracted extensive attention due to its excellent photoelectric properties.The traditional method of preparing two-dimensional films is carried out in an open system.However,phosphorus vapors has high saturated vapor pressure and is toxic,so they cannot be used to prepare silicon phosphide crystal materials.In view of the deficiency of the open system,a closed high vacuum system-CVT method was designed.As a traditional method of growing single crystal from purified raw materials,CVT method has been expanded to the field of growing two-dimensional thin films.In this paper,the thermodynamic and kinetic processes of the growth of silicon phosphide two-dimensional crystal materials were studied in detail by CVT method,and the photoelectric detection and electro-catalytic hydrogen evolution properties of silicon phosphide two-dimensional crystal materials were investigated.The main research results are as follows:In this paper,the preparation of sheet-like silicon phosphide and needle-like silicon phosphide is realized on mica and sapphire substrates by CVT method.CVT method was used to study the reaction process and mechanism of flake and acicular silicon phosphide in detail,and the influence of various reaction conditions on the growth results was explored.Using various characterization methods,it is proved that this method has the characteristics of large size and good controllability,and the CVT synthesis of monolayer silicon phosphide is realized for the first time.Make the photoelectric detector based on flake silicon phosphide and test the photoelectric performance of the device.The results show that the average photocurrent of the two-dimensional silicon phosphating photoelectric devices is about 843 n A,the optical response reaches 45 m A/W,the rise time and decay time of the time-resolved response are 11.5 ms and 18.5 ms respectively.Therefore,it has excellent photoelectric detection performance.Conduct macroscopic electrocatalytic hydrogen evolution test for acicular silicon phosphide.The test results showed that the overpotential was-278m V at the current density of 10 m A/cm~2,the corresponding Tafel slope was 68 m V/dec,and the hydrogen evolution performance of the needle silicon phosphate electrode after circulating in the electrolyte for 1000 times changed little compared with the first test,indicating that the electrode has good electro-catalytic stability.Therefore,it has excellent electrocatalytic hydrogen evolution performance.