Preparation Of Tellurium Thin Films By Energy Filtering Magnetron Sputtering And COMSOL Simulation Of Particle Distribution In The Field

Tellurium is an group VI elemental semiconductor with an narrow band gap of 0.34 eV.It shows p-type conductivity due to lattice defects acting as acceptors.Tellurium is located between Se and Po,and it owns metalliods,which makes it exhibit Multivalency and different Crystal structure.Becasue of its high electrical conductivity and good mechanical properties,Tellurium film has a series of excellent properties,such as thermoelectric effect,piezoelectric effect,nonlinear photoresponse,catalytic activity and photoelectric effect,which can be widely used in various fields especially in the field of microelectronic devices such as gas sensors,infrared detectors,optical storage and so on.Tellurium films have various preparation methods,such as molecular beam epitaxy,pulsed laser deposition,chemical vapor deposition,chemical synthesis,thermal evaporation,and so on.Te thin films prepared by magnetron sputtering have not been reported yet.DC magnetron sputtering has a large number of advantages:good controllability and repeatability,good adhesion to substrates,large film formation area,potential large-scale production,therefore which has been widely used for preparation of various films.However,the traditional magnetron sputtering technology also has some shortcomings.During the sputtering process,particles,the secondary electrons in the plasma with high energy has sputtering damage on substrate that is not resistant to bombardment and deposited non-resistant bombardment thin film,which can cause various defects in the film layer,therefore it has an adverse effect on the film properties.Meanwhile,the etch inhomogeneity of the magnetron sputtering target may cause uneven growth of the film,which affect the usage of film eventually.To solve these problems,our group has improved the traditional magnetron sputtering technology.We call the improved technology as the energy filtering magnetron sputtering technology(EFMS technology).In this paper,a series of films were prepared by EFMS technology.The effects of temperature and pressure on crystallization,optics,electrical properties of the films,and the photoelectric properties of the Te/Si heterojunction photodetector were investigated respectively.In addition,COMSOL Multiphysics software was used to simulate the energy and motion direction of the particles.The research contents include:Firstly,Tellurium film was prepared on a quartz substrate by EFMS technology.The effects of deposition temperature and deposition pressure on the structure,surface morphology,electrical properties and optical properties of Tellurium films were investigated by controlled variable method.They were characterized by XRD,Raman,SEM,Hall tester,ellipsometry,UV/VIS/NIR spectrophotometer.The result shows the preparation process has an effect on the crystallization,optical properties and electrical properties of the Tellurium film.(a)The film crystallizes better at 100°C,the surface particles are relatively larger and relatively more uniform than others',and the carrier concentration is higher than others'.At 200°C,the surface morphology of the film has been changed,the surface of the Te film changes from granular to staggered rod-like structure.At this time,The Te film had the smallest extinction coefficient,higher transmittance and lowest refractive index.(b)The film crystallized better at 0.75 Pa.It is known from the SEM image that the suface of the film is uneven and clustered at 0.75 Pa,and the film particle size is relatively more uniform at 1.0 Pa.The film transmittance is relatively high at 0.75 Pa,and the film has the lowest refractive index at 1.5 Pa.Sencondly,Tellurium film was prepared on Si substrate by EFMS technique.The impact of deposition temperature and deposition pressure on the structure,surface morphology and photoelectricity properties of Tellurium film was also studied by controlled variable method.They were characterized by XRD,SEM and Raman respectively.The result shows that the substrate affects the crystal orientation of the film,and deposition temperature and pressure have a great influence on the crystal quality of the film.The film prepared at 100 °C has good quality,and the quality of the film which was prepared under the pressure of 1.0 Pa is better than others'.The high-quality Te film was synthesized by energy filtering magnetron sputtering,and Te/Si heterojunction device was prepared in-situ by synthesis Tellurium film on plane Si substrates.The photoelectric characteristics of the prepared device were studied.The Te/Si heterojunction photodetector exhibited high sensitivity to the light in the wavelength range of 405 nm-1300 nm.Finally,based on the previous research results of our research group,the electromagnetic field distribution of the deposition chamber was simulated by COMSOL Multiphysics software,and the energy of the deposited particles and the distribution of various particles in the deposition chamber were simulated.We know electrons are mainly distributed in the vicinity of the substrate,and the ions are mainly concentrated in the vicinity of the target.In addition,we also simulate the effect of voltage on the DC discharge particle energy of the plasma and the particle distribution.The higher the voltage,the greater the energy obtained by the electron,and the higher the argon mass fraction,but the lower the voltage,the higher the argon ion density.