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Study on the Structural and Magnetic Properties of Fe(Cu) Doped Ge(Si) Based Diluted Magnetic Semconductor Films

Author: GaoWeiXia
Tutor: HouDengLu
School: Hebei Normal
Course: Condensed Matter Physics
Keywords: Magnetic semiconductors Ion Implantation Magnetic domains Transport properties Hall Effect
CLC: O472.5
Type: Master's thesis
Year: 2010
Downloads: 57
Quote: 1
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Abstract

In today's era of rapid development of information, information transmission and storage are still processed by traditional methods - were controlled electron charge and spin of electrons to achieve. With the increasing demand for the amount of information, the traditional semiconductors and ferromagnets lack of independent work to bring more and more prominent, set the electron charge and spin in one of the diluted magnetic semiconductor materials has become most people interested in research. Diluted magnetic semiconductors as transition metals or rare earth doped magnetic elements, making these materials compared with conventional semiconductors, there were many strange features, have a good application prospect. Mn-doped Ⅳ group based diluted magnetic semiconductors theoretical and experimental advances have been achieved gratifying results, but on its magnetic origin and the specific application of the device remains to be further studied. This work was selected transition elements Fe and Cu, on the Si / Ge-based semiconductor doping, specifically as follows: 1. Using magnetron sputtering on Si substrates were prepared Fe-doped Ge1-xFex film series, the substrate temperature was 473 K, 873 K after vacuum annealing 20 min to obtain a sample. X-ray diffraction (XRD) analysis showed that all samples have the structure of Ge cubic structure, not found in other impurity phase. Fe in the sample exists mainly in the form of Fe2 ions, while a small amount of Fe0; Ge Ge0 mainly in the form of elements present in the sample, a small amount of Ge-O bond and Ge-Fe bond. 11.3% Fe doping concentration of Fe3 ions are present in a sample. Magnetic measurements show that the sample has a weak low Curie temperature of about 300 K, from the random distribution of the ferromagnetic magnetic Fe atoms. 2 with a metal vacuum arc evaporation and Kaufman ion implantation in n-Si (100) substrate, the CCP into Fe, N ions, prepared Fe, N codoped Si (Fe, N) thin films. X-ray diffraction (XRD) structural analysis showed no change in the ion implantation of the cubic lattice structure of the substrate, nor the formation of other impurities in the second phase. X-ray absorption fine structure (XAFS) showed that low doses of injected sample substitutional Fe ions in the high-dose injection in a sample FeSi2 compound. Magnetic force microscopy (MFM) observed magnetic domain structure, magnetic measurements showed that low-dose infusion (2.0 × 1016 cm-2) samples have the greatest moment about 0.46μB/Fe, in situ annealing and after annealing are weakened ferromagnetism. Hall measurements show that the sample is an n-type conductivity, the saturation magnetization as electron carrier concentration increases. Does not depend on the sample of the magnetic carriers, but in the alternative position of the Fe from the magnetic atoms. 3, with the metal evaporation vacuum arc ion implantation technique, in n-Si (100) substrate to obtain the Cu ion implantation Si: Cu film. X-ray diffraction (XRD) measurements show different doses by the sample after the Cu ion implantation into a single crystal Si polycrystalline Si lattice structure, while the gap of Cu, Si and Si vacancy defects such as gaps formed, but not found in other impurity phase . Often injected into the sample state, Cu in the form of Cu ions, N2 gas atmosphere by rapid thermal annealing, a small part of Cu2 ions appears. Hall effect measurements show that the Cu ion implantation allows the parent of n-type Si into p-type conduction. Magnetic measurements show that the sample has a temperature ferromagnetism, the magnetic carriers from the hole of the Cu ion transfer between the Si vacancies ferromagnetic interaction.

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