Ion Implantation Doping And Annealing The Study Of The Impact Of Treatment On The Properties Of Zno Films

Zinc Oxide(ZnO) is an important wide and direct band gap(Eg=3.37eV at room temperature) semiconductor materials,which has large exciton binding energy of 60meV.ZnO has been recognized as a promising material for use in many fields such as ultraviolet(UV) detectors,short-wavelength light-emitting diodes(LEDs),laser diodes(LDs),and solar cells,etc.In order that ZnO films can be applied in various optoelectronics devices,it is necessary that we should improve(or change) physical and chemical properties of ZnO thin films,both doping and thermal annealing are very important means.In particular,it is very important that p-type ZnO thin films are obtained by doping method.At present,The ion implantation is an attractive doping technique for using in semiconductor materials.In this thesis,We study that properties of ZnO thin films are enhanced(changed) by the ion implantation and thermal annealing.X-ray diffraction(XRD), photoluminescence(PL) spectra,X-ray photoelectron spectra(XPS),optical transmittance spectra,four-probe method and so on had been utilized to characterize the structural,optical and electrical properties of the samples.The results have been listed as follow:1.Zn ions of dose 1×10¹⁷cm^-2 were implanted at 56 KeV into ZnO films deposited on quartz glass by the sol-gel process.After ion implantation,the as-implanted sample was annealed in argon ambient at different temperatures from 500-900℃.Measurement results showed that the intensity of all diffraction peaks and the near band edge(NBE) emission peak and the deep level emission(DLE) peak evidently decreased after ion implantation,all diffraction peaks intensity were recovered by annealing at～700℃.The absorption edge were observed to have a continuous blueshift with increasing annealing temperature when it was less than 600℃,while the absorption edge was found to have a gradual redshift with increasing annealing temperature when it exceeded 600℃.Both NBE and DLE were enhanced with increasing annealing temperature.2.ZnO:Al thin films doped with 1%aluminum(Al/Zn=1%) are deposited on(0001) sapphire substrates by the sol-gel technique,N ions of dose 1×10¹⁷cm^-2 were implanted at 56 KeV into ZnO:Al films,the as-implanted sample was annealed in N₂ ambient at different temperatures from 500-900℃.Measurement results showed that the crystal quality of the thin films became good gradually with increasing annealing temperature when it was below 800℃.Both the NBE peak and the DLE band were enhanced with increasing annealing temperature when it exceeded 600℃.When annealed at 600℃, the resistivity of the sample was only 83Ω·cm.3.ZnMgO:Al(Mg/Zn=10%,Al/Zn=1%) films deposited on quartz substrates by the sol-gel process,N ions of dose 1×10¹⁷cm^-2 were implanted at 60 KeV into the as-prepared sample.After ion implantation,the as-implanted sample was annealed in N₂ ambient at different temperatures from 500-800℃.Measurement results showed that after ion implantation,all diffraction peaks disappeared,the optical transmittances in the visible region evidently decreased,the optical band gap of the sample had redshift,both the intensity of the NBE peak and the DLE peak decreased.After post-implantation annealing,the diffraction peaks appeared and gradually enhanced with increasing annealing temperature,the optical transmittances in the visible region continuously increased and both the NBE and the DLE enhanced with increasing annealing temperature.4.ZnO:Al thin films doped with 0.1%aluminum(Al/Zn=0.1%) were deposited on quartz glass by the sol-gel technique.The as-prepared sample was annealed in argon ambient at 500℃and annealing time was varied between 1 and 5h. Measurement results showed that when annealing time was 1h,the sample exhibited preferred c-axis orientation,the DLE was enhanced,the optical transmittances were about 80%in the visible region and the resistivity of the sample was only 4×10^-2Ω·cm. When annealing time exceeded 1h,the crystal quality became poor and the resistivity was increased continuously with increasing annealing time.