Study Of Structures And Physical Properties In Ion Implanted ZnO Films

Owing to its wide direct band gap and high exicton binding energy, ZnO hasconsiderable potential for applications in the optoelectronic devices field. In addition,ZnO is also a potential ferromagnetic material arising from carriers at roomtemperature, and is hopeful to realize diluted magnetic semiconductor material. In thisthesis, P ions were implanted into the pure and B doped ZnO films, respectively. Feand C ions were sequentially implanted into other pure ZnO films. Techniques, suchas, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS）,photoluminescence （PL）, Ultraviolet-visible （UV-Vis） spectroscopy and Physicalproperties measurement system （PPMS） were used to characterize theimplantation-induced modifications in structures, optical, electrical and magneticproperties of these films systemly.Firstly，it is found that resistance is very large in ZnO film deposited on fusedsilica glass substrates by rf magnetron sputtering. However, the film implanted with Pions in terms of different energy/fulence combinations, i.e.¹⁵0keV/1.5×10¹⁵ions/cm²，80keV/5.5×10¹⁴ions/cm²，and35keV/².5×10¹⁴ions/cm², shows holeconductivity, and has a low carrier concentration. After annealing at500oC, carrierconcentration increases distinctly in the sequentially implanted film. However, boththe un-implanted and the singly implanted film(¹⁵0keV/1.5×10¹⁵ions/cm²)show ntype conductivity. Further increasing annealing temperature up to700oC, all the filmsshow large resistance and close to the apparatus limits. Moreover, structures andoptical properties of these films have also been systematically investigated. It seemsthat P substitutes O （PO） and/or Zn vacancies （VZn） play an important role forelectrical properties in the sequentially implanted film.Secondly，the ZnO:B film deposited by MOCVD presents high crystalline quality.XRD results reveal a mainly （110） preferred growth orientation. Structures of thefilm has no obvious change when P ions were implanted at40keV with a fluence of5.0×10¹⁴ions/cm². However, as the fluence increases to².5×10¹⁵or1×10¹⁶ions/cm²,the intensity of ZnO（110）peak decreases, and the FWHM increases. Moreover, theaverage transmittance value reduces obviously in visible region after implantation ofP ions. The ZnO:B film has a low resistivity, which increases with the fluence of implanted P ions. When the fluence of P ions increases to1×10¹⁶ions/cm², theresistivity reaches to0.37cm.Finally，magnetic measurements show that ZnO films deposited on glass presentroom temperature ferromagnetism. Nanoparticles were formed when single Fe ionsimplanted into ZnO film at1²0keV with a fluence of5×10¹⁶ions/cm², which have nocontribution to the enhancement of magnetism but slightly decrease the saturationmagnetic moment. In addition, the ferromagnetism has not been enhanced whensingle C ions were implanted into ZnO film at²0keV with a fluence of3×10¹⁵ions/cm². However, the magnetic moment increases distinctly in the Fe and C ionssequentially implanted film. Based on the changes induced in structural and opticalproperties, the effect of magnetic enhancement at room temperature has beententatively interpreted.