Preparation Of MgAlSnO Thin Films By Magnetron Sputtering And Their Properties

The display technology plays a significant role in the electronic information industry.Whether large-scale produced TFT-LCD or the next generation display AM-OLED,TFT arrays are their core technology.Recent years,the oxide semiconductor TFT to be the core technology of next generation TFT due to its high mobility,transparency in visible region and low temperature deposition.In this paper,the MgAlSnO thin films were deposited by magnetron sputtering for the first time and the preliminary experiment in TFT with MATO as the active layer was made.The main work and results summarized as follow:1.Firstly,we made a detailed experimental study in the effects of process parameters on the deposition of MgAlSnO thin films by magnetron sputtering to obain the best parameters.It is found that when the sputtering pressure is 0.6Pa,the sputtering power is 100 W,the film has the fastest growth rate and the best surface morphology,and a good amorphous state under the thickness of 120 nm.2.The surface morphology,optical transmittance and electrical properties of MgAlSnO thin films with different concentrations of Al doped Mg₂SnO₄ have been studied.The results indicate that with the increase of the doped concentration,the surface roughness of the films decreases.And the film become more smooth and compact,so the doping of Al element is helpful to improve the film quality.The transmittance of MgAlSnO films with different doping ratios in the visible band is not the same,but they are all more than 92%.The electrical performance test of their MSM structures shows that the current density and voltage are remained linear,which indicate that the MATO films have good ohmic contact with Al and ITO electrodes.The Mg₂SnO₄ film and MATO?1:1:2?film have good conductivity.3.The qualitative analysis of the composition of the material elements on the MATO thin films by EDS shows that there are some differences between the film and the target.However,when the Al is low doping in the target,the film can still contain a considerable proportion of Al.4.When a small amount of oxygen?O₂/Ar=2/48?was used,the transmittances of Mg₂SnO₄ film and MgAlSnO films were improved to 93%.Some films have lower conductivity.It can be seen that the metal atoms will continue to be oxidized when exposed to oxygen and the transmittance be increased.And the decrease of oxygen vacancies in the films leads to the decrease of the carrier concentration and the poor conductivity.5.The Mg₂SnO₄ film and MgAlSnO films are amorphous after annealing at 300 ?,and their surface is smooth and compact.The conductivity is decrease mainly due to the recombination of atoms in the films after annealing at high temperature,which results in the decrease of oxygen vacancy and the decrease of the carrier concentration.6.On the basis of the good film properties,the MATO thin film was used as the active layer in the TFT and a preliminary experiment was carried out on the fabrication of the small size TFT device with the photolithography process.