Preparation Of ZnO Diluted Magnetic Semiconductors By Hydrothermal Method

Diluted magnetic semiconductors (DMS) is a kind of material that it can successfully combine the magnetism and electronics in a single substance. DMS is recognized as the base of spin-electron theory, which has some good magnetic performance, magneto-optic and magneto-electric nature,which made its widespreadly applied in such fields as high density nonvolatile memory, magneto-inducer, semiconductor integrated circuit, semi- conductor laser, spin quantum computer, and so on.ZnO matrix diluted magnetic semiconductor crystals were prepared by hydrothermal method doped with Ni²⁺,Cr³⁺,Co²⁺ and Mn²⁺ doped. Some process factors were studied such as different prescour preparation, mixing time, reaction temprature, reaction time, mineralizer type and its concentration and doping content, etc. XRD and UV-Vis were employed to demonstrate the presence of doped ions in substitution of Zn sites. FE-SEM images show as-prepared samples crystals pattern. UV-Vis measurements demonstrate the presence of doped ions in substitution of Zn²⁺ and forbidden band width can be calculated. EDS patterns show the actual doping concent of the final product. Room temperature VSM reveals magnetic properties of the samples.Zn1-xNixO diluted magnetic semiconductor was prepared by hydrothermal method with the Ni²⁺ of 5%²0%(Atomic%). NaOH of 3mol/L were used as the mineralizer. Ni(OH)2 phase appeared when the concentration of NaOH up to 5 mol/L. The forbidden band width were sequentially 3.20eV,3.19eV,3.15eV and 3.17eV with doping content x=0,0.05,0.1 and 0.2, only when x=0.05 and 0.1, as-prepared samples were good. The pure Zn0.95Ni0.05O was obtained with prescour prepared by method of precipitation. XRD and UV-Vis are employed to demonstrate the presence of Ni²⁺ in substitution of Zn²⁺ sites. XRD analysis indicates that the as-prepared Zn0.95Ni0.05O has the pure ZnO wurtzite structure. UV-Vis measurements demonstrate the presence of Ni²⁺ in substitution of Zn²⁺. Room temperature VSM reveals a ferromagnetic loop of the Ni-doped ZnO samples and EDS shows actual content of Ni²⁺ is 3.20%(Atomic%)。Zn1-xCrxO diluted magnetic semiconductor was prepared by hydrothermal method at 240℃for 24h with NaOH of 3mol/L was used as the mineralizer. The best mixing time is 7h⁸h and the compactness is 75%. Impurity phase would increase with Cr³⁺ concent from 0.05 to 0.20. X-ray diffraction measurements indicates that the as-prepared Cr-doped ZnO (x=0.05,0.1,0.15) has the pure wurtzite structure which demonstrates the presence of Cr³⁺ in substitution of Zn²⁺. FE-SEM analyses show that nanocrystalline powders changing from short stylolitic structure to long stylolitic structrue when the Cr³⁺ concentration of x≥0.2. Room temperature VSM reveals a weakly paramagnetism loop.Zn1-xCoxO diluted magnetic semiconductor was prepared by hydrothermal method at 200℃and 240℃for 24h with the Co²⁺ doping content of 5%¹5%(Atomic%). NaOH was used as the mineralizer. X-Ray Diffraction (XRD) spectras indicate that the as-prepared Co-doped ZnO had the pure ZnO wurtzite structure. UV–Vis spectroscopy shows that the Co²⁺ are substituted to Zn²⁺ in ZnO matrix and its peak value appears at 570nm, 610nm and 655 nm. Room temperature VSM reveales a paramagnetic loop of the Co-doped ZnO samples. FE-SEM analyses explay that nanocrystalline powders of pure Zn095Co0.05O and Zn09Co0.1O could be prepared by the hydrothermal method.Zn_0.95Mn_0.05O and Zn_0.9Mn_0.1O crystals were synthesied by hydrothermal method at 240℃with NaOH of 3mol/L. Zn_0.85Mn_0.15O crystals were prepared by hydrothermal method at 240℃with NaOH of 5mol/L. Zn_0.9Mn_0.1O and Zn_0.85Mn_0.15O crystals appeare ferromagnetic property at room temprature.