Study On The Preparation Of AlN Thin Films And The Effect Of Oxygen Contaminantion

Aluminum nitride(AlN)thin film is a kind of ultra wide band gap semiconductor material with great commercial potential in the third generation of semiconductor materials.It has a wide range of applications due to its excellent physical properties.In this paper,polycrystalline AlN thin films were prepared on single crystal silicon substrate by RF Reactive Magnetron sputtering,using Al target(99.99%)as sputtering target,high purity argon as sputtering gas and high purity nitrogen as reaction gas.AlN was characterized by XRD,step profiler,TEM,EDS,XPS,Transmission and PL.The effects of deposition time and substrate temperature on the crystal structure and deposition rate of AlN films are discussed.The influence of oxygen contaminant on the preferred orientation of AlN films was studied.The band gap and luminescence of AlN films were characterized by transmission and PL spectra.The experimental results show that the deposition time has an effect on the crystal quality and deposition rate of AlN films,but has no obvious effect on the preferred orientation of AlN films.The substrate temperature has an obvious effect on the preferred orientation of AlN films.When the temperature rises to 300 ?,AlN films grow along the(002)crystal surface.The deposition rate increases first and then slows down with substrate temperature.This is because the growth factor on the substrate surface has higher energy when the temperature increases,which promotes the adsorption,migration and diffusion of particles.However,too high temperature makes desorption obvious,which leads to the decrease of deposition rate of AlN films.The oxygen contaminant has a very obvious effect on the preferred orientation of AlN films.When there are more oxygen contaminants,AlN films grow preferentially along(100)crystal plane;when there are less oxygen contaminants,AlN films show(002)crystal plane preferred orientation.In addition,the oxygen contaminant also has significant effects on the photoluminescence of AlN films.When there are more oxygen contaminants,there are more strong luminescent peaks in AlN.But the photoluminescence peaks of AlN films are weak and wide when oxygen contaminants are less.