Zn1-xCoxO (x=0.01, 0.02) dilute magnetic semiconductor thin films deposited on Si (001) substrates at 650℃ by pulsed laser deposition method were studied by X-ray absorption fine structure, X-ray diffraction and magnetic measurement. The typical ferromagnetic hysteresis curves were obtained by superconducting quantum interference device magnetometry at room temperature. The X-ray diffraction results showed that Zn1-xCoxO films were of the wurtzite structure. The X-ray absorption fine structure results revealed that the Co atoms were incorporated into the ZnO lattice and located at the substitutional Zn sites, and a homogeneous phase of Zn1-xCoxO was formed. Comparing the experimental curves with the theoretical calculation results, the additional peak C was assigned to the oxygen vacancies, which indicated that the ferromagnetism of Zn1-xCoxO films was strongly correlated with the existence of oxygen vacancies.
The hole concentration and strain relaxation degree in the diluted magnetic epitaxial film of GaMnAs are affected by the Mn concentration. The result from Raman scattering spectrum experiment has shown that the hole concentration in ultra-thin GaMnAs sample with Mn concentration of 3% is greater than that in sample with Mn concentration of 2% , while the hole concentration in sample with Mn concentration of 4% is less than that in sample with Mn concentration of 3%. Based on the theory of strain relaxation and investigation by HRXRD, it was indicated the samples with Mn concentration of 2% and 3% are in quasi-coherence or with low relaxation degree, respectively. On the other hand, the sample with Mn concentration of 4% obviously has a greater relaxation degree than that with 3% concentration. Therefore, it is suspected that the status of quasi-coherence or low relaxation degree hardly affects the hole concentration with the change of the Mn concentration. However, the strain relaxation status of large relaxation degree results in more defects in the epitaxial layer which affects the energy band and level thus decreases the hole concentration dramatically.
The structure of MnxGe1-x dilute magnetic semiconductor thin films prepared by magnetron co-sputtering has been studied by X-ray diffraction (XRD) and X-ray absorption fine structure (XAFS) techniques. The XRD results show that in the MnxGe1-x thin film with low Mn doping concentration (x=0.070), only diffraction peaks attributed to crystalline Ge can be observed. In samples with high Mn doping concentrations (x=0.250, 0.360), the secondary phase Ge3Mn5 appears, and its content enhances with Mn doping concentration. The XAFS results indicate that for the Mn0.07Ge0.93 thin film, Mn atoms are mainly incorporated into the Ge lattice and located at the substitutional sites of Ge atoms with the ratio of 75%, while for the Mn0.25Ge0.75 and Mn0.36Ge0.64 samples, most of the Mn atoms are aggregated to form Ge3Mn5.
NiO films are prepared with radio frequency magnetron sputtering. Ellipsometric experiment results show that NiO film is transparent for visible light,and its refractive index can be modified by changing Tsub and annealing temperature. Scanning electron microscopy and X-ray diffraction experiment results show that Tsub and annealing temperature can modify the morphology and crystal structure of NiO film which can further modify the conductivity of NiO. The optimized NiO film is used in polymer solar cell (PSC) as an anode blocking layer. The experimental results show that NiO is a better candidate than the PEDOT:PSS often used as an anode blocking layer for PSC. The power conversion efficiency of PSC with NiO reaches 2.26% which is three times as high as that with PEDOT:PSS.
The influence of the major compensating defects As antisites (AsGa) and Mn interstitials (MnI) in the Ga0.946Mn0.054As diluted magnetic semiconductor (DMS) were studied by X-ray absorption spectra (XAS). The experimental results show that the defects in Ga0.946Mn0.054As grown at lower temperature (TS=200℃) is mainly AsGa, but at TS>230℃ MnI is the major defects. On the other hand, a higher LT-annealing temperature (250℃) can remove MnI out of the Ga0.946Mn0.054As lattice, and the highest Curie temperature (TC=130 K) is reached. Moreover, it is indicated that the LT-annealing process can increase the number of MnGa atoms by reducing the concentration of AsGa defects and driving MnI defects to fill up the holes left by AsGa.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.