Preparation And Electrical Properties Of High-resistance AZO Thin Films

As a new kind of semiconductor material,aluminium zinc oxide?AZO?film has attracted widespread attention of scientists as soon as it appears.At present,the research about AZO film is mainly focused on its transparent conductive.And AZO films have been deeply studied in their optoelectronic performances,crystal structures,coating technologies and the developments and applications of related devices.It is found that the AZO film composed of conductor ZnO and insulating Al2O3 has a wide range of resistance adjustability to satisfy the resistivity requirements of the conductive layer of the micro-channel plate.Unlike the low resistance characteristics of the traditional AZO transparent conductive film,the research on the high resistance properties of the AZO film can provide some technical support for improving the electrical properties of the microchannel plate electronic multiplier devices.However,few studies about the photoelectric properties of the high resistance AZO films are reported.In this study,the high-resistance AZO film is prepared by atomic layer deposition?ALD?and annealing process.First,the ALD process parameters are optimized,and the effects of Al₂O₃ cycle percentage,sub-cycle coefficient and growth temperature on the surface morphology and electrical properties of AZO film are studied.And the effects of precursor pluse time and growth temperature on the coating degree of AZO film are investigated.Then,the AZO film treated by different annealing processes is characterized and analyzed.The effects of the annealing temperature and time on the surface morphologies,structures and the electrical stabilities of AZO film are investigated.The results show:When the percentage of Al₂O₃ cycle is between 40%and 80%,and the sub-circulation coefficient is not bigger than 10,the sheet resistance of the film varies between 7.56×10¹¹?/?and 6.82×10¹³?/?,which can meet the resistivity requirements of the microchannel plate.Through SEM and AFM characterization,it is found that the prepared AZO film is smooth and uniform,and the higher the cycle percentage of Al₂O₃ is,the more smooth the film surface is,which agrees with literatures.The prepared films are all thinner than the designed ones?200 nm?,which proves that ZnO is corroded and lost during the growth process of AZO film.The coating property of AZO film can be improved by changing the growth temperature and precursor ventilation time.When the growth temperature is 200^?C and the precursor pluse time is over 2 s,the surface coverage of AZO film reaches 100%.After the annealing process at 400^?C for 6 h,the surface of AZO film becomes smooth and its roughness is only 0.185 nm.When the test voltage ranges from10 V to 1000 V,the measured block resistance of AZO film is basically stable,with the maximum of 5.76×10¹²?/?and the minimum of 5.55×10¹²?/?.The prepared AZO film meets the application requirments of micro-channel plate electronic multiplier.