Si Of Penetration And The Influence Of Doping On The Structure And Characteristics Of Azo Film

ZnO is a Ⅱ-Ⅵ semiconductor material with a wide direct band gap （3.37eV at roomtemperature）, and has a hexagonal wurtzite structure. ZnO and Al: ZnO （AZO） exhibitexcellent performances in electro-optical, piezoelectric, pyroelectric, ferroelectric andoptoelectronic devices and many other fields.With the further research and application of ZnO and AZO thin films, the infiltrationor doping of Si has aroused wide attentions, which is mainly reflected in two aspects:1. ZnO or AZO thin films are usually deposited on Si single crystal or polycrystallinesubstrates in the related research and application, and Si in the substrate will permeate tothe film and form ZnO:Si or AZO:Si transition layer during the deposition process.Therefore two issues must be paid attention:1)Influence of transition layer’s thickness orSi penetrative depth on the main bodies structure and properties of ZnO or AZO films；2)Influence of substrates’ temperature during the deposition process on the transitionlayers’ structure and performances;2. The property of ZnO or AZO film could be modulated by Si doping, but the influence ofSi doping concentration on the structure and properties of ZnO or AZO film is unclear.In view of the above issues, Al and Si co-doped ZnO thin films （AZO, Si） weredeposited on the quartz and Si substrates by RF reaction magnetron sputtering methodusing ZnO:Al:Si powder sintering ceramic targets as sputtering target and Ar as sputteringgas. The research mainly includes three aspects as follows:1. The influence of film thickness （equivalent to the thickness of transition layer or theSi penetration depth） on the electrical and optical properties of AZO films are studied,which deposition temperature is maintained at400℃and Si doping concentration is set as1.2wt%,.The results show that the resistivity, carrier concentration and mobility of the thinfilms are strongly dependent on the film thickness. The film with about19nm thicknesshas the lowest carrier concentration and mobility and larger resistivity, which presents p-type conductive properties. With the film thickness increasing, the film carrierconcentration and mobility become larger and the resistivity decreases and tends to bestable. The resistivity closes to a minimum around7×10-3·cm when the film thickness isabout396nm, which carrier concentration and mobility are respectively1.54×10²⁰cm-3and5.66cm²V^-10s^-1.The influence of film thickness（penetrative depth or transition layer thickness of Si）on the film properties and relative mechanism are studied by using the films X-raydiffraction （XRD） pattern、X-ray photoelectron spectroscopy （XPS） and Ultraviolet-visible（UV-Vis） transmission spectra. As is shown in the study that the effect of Si penetration onthe film characteristics is obvious while the film is thin （about20nm）, which is mainlyreflected in the formation of Si-O-Zn bond even Zn²SiO₄particles; the influence of Sipenetration （or Si intermediate layer） on AZO becomes gradually smaller with theincreasing of the film thickness, and could be ignored when the thickness is around300nm;The resistivity closes to be the minimum value while the thickness is about400nm; Thefilm properties such as resistivity, carrier concentration, and optical band gap could bemodulated by controlling the film thickness.2. The influence of deposition temperature on the structure and property of AZO:Sifilms such as surface morphology, optical properties and electrical properties are studied,with Si weak doping （1.0wt%concentration） and160nm film thickness.The result shows that the film samples get the best crystallinity with about400℃deposition temperature and have very obvious C axis preferential orientation, which （002）XRD diffraction peak locates at34.45°almost the same as that of standard AZO films, andthe resistivity closes to a minimum around3.6×10-4Ω·cm, carrier concentration andmobility are6.09×10²⁰cm–3and18.5cm²V^-10s^-1respectively. In addition, the averagetransmission rate of AZO:Si thin film has a very slight variations with the depositiontemperature being changed.3. The influence of Si doping concentration on structure and properties of AZO:Sithin films such as surface morphology, optical properties and electrical properties arestudied with400℃deposition temperature and160nm film thickness. The result shows that Si doping can significantly affects film optical band gaps, that is to say, filmabsorption edge will show a blue shift, namely shifting to the short-wave direction, withthe increasing of Si doping concentration. Nevertheless, Si doping will lead tocrystallization deterioration of AZO film, and even disappearance of typical AZO XRDdiffraction peak with high doping concentration （1.6wt%）; The film conductivity alsobecome worse with the increasing of Si doping concentration. It is thus clear that thedoping concentration of the Si should not be too large, preferably less than1.2wt%, so asnot to cause AZO main body structure and performances obvious changes.