Study On The Synthesis And Physical Properties Of Zno-based Diluted Magnetic Semiconductors

In recent years, based on the research of produce, transportation and manipulation of electron spin, a new subject called"Spintronics"emerges. Due to the possibility of controlling both the spin and charge of electron, spintronics might bring a new revolution in the field of trasitional electronics. Meanwhile, as the footstone of designing spin-based devices, diluted magnetic semiconductors have now draun dramatic attentions.The research on diluted magnetic semiconductors is one o f the frontiers of modern physics. As one of the most promising DMS candidates, transition metals doped ZnO has been receiving great attention very recently. Although there have been many inspiring results in both theoretic and experimental fields, some questions are still to be further solved. The researchers have done some research on the micro-structure,magnetic,electronic transport,magnetic resestance,optical,magneto-optical and other properties of magnetic semiconductors, the results are inconsistent even contradictory. The origin of ferromagnetic is the focus of debate of oxide magnetic semiconductor. Researchers believed the magnetic come from the carrier induced exchange interaction, double exchange et al intrinsic mechanisms. Also, it may be due to the low dissolve of the transition elements in semiconductor which lead to the ferromagnetic impurity phase. Therefore, there are many issues to be solved further. In this paper, we mainly focus on the ZnO-based DMS to do some research.①We have investigated the properties of Mn-doped ZnO nanocrystalline film grown on zinc foil by corrosion-based strategy. The X-ray photoelectron spectroscopy show the manganese doped in ZnO exists as Mn2+. UV-vis spectra exhibit a decrease in the band gap after being doped with Mn. The photoluminescence spectrum of the Mn-doped ZnO film shows the two strong new peaks, blue emission peaks centered at 424 nm and 443 nm, except the UV emission peak owing to the band gap of ZnO semiconductor. The magnetic property of the Mn-doped ZnO exhibits a room temperature ferromagnetic characteristic with a saturation magnetization (Ms) of 0.3902×10-3 emu/cm2 and a coercive field of 47 Oe.②Ni-doped ZnO rod arrays have grown on zinc foils by corrosion-based strategy. The doping Ni content could be controlled by varying the reaction time. The X-ray diffraction and X-ray photoelectron spectroscopy indicated that the Ni ions are incorporated into the ZnO lattices as Ni2+ ions. However, NiO forms when the Ni content is more than 5 at %. Photoluminescence peak of the rod arrays shifts to a little longer wavelength and its intensity decreases with the increase of Ni content. The green light emission as a result of oxygen vacancies was observed when excessive Ni ions were doped in ZnO. The rod arrays have exhibited room-temperature ferromagnetic behavior with the remanence of 0.454, 0.605 and 0.526 emu/cm3 for the Ni concentration of 2.38, 4.35 and 5.54 at%, respectively.③Fe-doped ZnO rod arrays have grown on zinc foils by corrosion-based strategy. The doping Fe content could be controlled by varying the reaction time. The X-ray diffraction and X-ray photoelectron spectroscopy indicated that the Fe ions are incorporated into the ZnO lattices as Fe3+ ions. However, ZnFe2O4 forms when more Fe ions incorporated into the ZnO. Photoluminescence peak of the rod arrays shifts to a little longer wavelength and its intensity decreases with the increase of Fe content. Blue emission peak can be found in these three sampls. The green light emission as a result of oxygen vacancies was observed when excessive Fe ions were doped in ZnO. The rod arrays have exhibited room-temperature ferromagnetic behavior with the remanence of 0.372, 0.613, 0.557 emu/cm3 and the coercivity are 99.33, 117.3, 24.4 Oe respectively.④Because the Cu is non-magnetic ions, to study the Cu doping could give rise to ferromagnetism or not is very important. Cu-doped ZnO rod arrays have grown on zinc foils by corrosion-based strategy. PL spectra exhibit a red shift for the UV emission peak after being doped with Cu. There are two emission peaks in blue and green region for the interstitial zinc defects and oxygen vacancy defects caused by Cu ions incorporation. The magnetic property of the Cu-doped ZnO exhibits a room temperature ferromagnetic. The Cu is nonmagnetic ions. The room temperature ferromagnetic caused by Cu ions'incorporation is a strong evidence for the ferromagnetic is intrinsic of the samples.