Dissertation > Excellent graduate degree dissertation topics show

ZnO Doped Co-Based Diluted Magnetic Semiconductors by Pulsed Laser Deposition

Author: SuXueQiong
Tutor: WangLi
School: Beijing University of Technology
Course: Optics
Keywords: Diluted magnetic semiconductors Pulsed laser deposition Solid-phase sintering method Zinc oxide Zn0.9Co0.1O
CLC: TN304.21
Type: Master's thesis
Year: 2010
Downloads: 99
Quote: 0
Read: Download Dissertation

Abstract

Herein, the dilute magnetic semiconductor (diluted magnetic semiconductor, DMS) refers to the transition metal or rare earth element (e.g.: Mn, Fe, Co., of Ni, Cr and Eu, etc.) by the magnetic partial substitution of Ⅱ - Ⅵ, Ⅳ - VI, some elements of the family, or Ⅲ - Ⅴ family semiconductor formed a new class of semiconductor materials, at the same time has the charge of an electron can be adjusted and the characteristics of the two kinds of degrees of freedom of the electron spin. Wherein the magnetic ion 3d electrons and conduction band sp electronic coupling effect between the (SP-D), and (dd) coupling between the magnetic ion exchange interaction makes a diluted magnetic semiconductor material has many novel magneto-optical and magnetic and electric properties, broad application prospects in the field of high-density non-volatile memory, magnetic sensors, optical isolators, semiconductor integrated circuits, semiconductor lasers and spin quantum computer. This paper describes the history of diluted magnetic semiconductor development and research status, by pulsed laser deposition method in the experiment, the first attempt of ZnO target and film, as the basis for successful preparation of cobalt-doped ZnO target and film. Electromagnetic and structural properties of the material of the optical testing to study the relationship between material properties and the preparation method and process. The main contents include: (1) the use of the GCR-170-type pulse laser third harmonic of the Nd: YAG (355 nm), sapphire Al2O3 (0001) substrate prepared by pulsed laser deposition (PLD) at different temperatures ZnO film. Through an atomic force microscope (AFM), the Raman spectra, photoluminescence (PL) spectra, infrared transmission spectra, and the Hall effect and the surface roughness analyzer ZnO films tested. Analysis of the surface morphology and optical properties of films with different substrate temperatures, while the film structure and the thickness of the test. Studies have shown that: the temperature of the substrate surface morphology, optical and structural properties of ZnO thin films are important process parameters, especially compact and uniform ZnO thin films deposited at 500 ℃ and showed strong UV emission peak. (2) using different sintering temperature solid state reaction prepared by single factor experiment on the same blend component sample processing Zn0.9Co0.1O bulk material, and were Zn0.9Co0.1O material X-ray spectroscopy (XPS), MT, Fourier transform infrared absorption spectra (FTIR), X-ray diffraction (XRD), Raman spectra (Raman) and photoluminescence (PL) spectrum of test and analysis. The experimental results show that: CO2 incorporated into the ZnO lattice, and good substituted Zn2's position and is surrounded by oxygen surrounded, the formation of a Co-O bond. Sintering temperature on the Co doping concentration has little effect, and to exclude the possibility of the formation of Co clusters or CoO crystal phase. Sintering temperature constraints of CO2 incorporated into the ZnO lattice and substituted Zn2 a position without affecting the structure of ZnO, the material prepared at 1200 ℃ maintain a wurtzite structure, also seen from the Raman spectrum characteristics of the phonon structure of CO2 and Co ions into ZnO lattice so that the optical band gap narrowing phenomenon. (3) using pulsed laser deposition method, based on the selected substrate temperature, the cobalt-doped zinc oxide films were successfully prepared. By atomic force microscopy (AFM) on the samples prepared test, the observed growth of the surface morphology of the samples graphics than non-doped ZnO films lot of smooth; experiments on the characterization of thin film X-ray diffraction (XRD), the measured CO doped miscellaneous not destroy ZnO wurtzite structure, surface morphology and structure of the 500 ° C sample; film XPS analysis showed that the Co ions in the sample in the form of divalent and with increasing substrate temperature Co content is also rising, but when the temperature reaches 800 ℃, the solubility limit of more than Co Co clusters phenomenon appeared. To further validate the Co ions into the crystal lattice of ZnO samples prepared on different substrate temperature measurement of the transmission spectrum, from all-optical transmission spectrum see the the broadband energy gap broadening occurs, and discussed an internal mechanism. While the substrate temperature rise caused by the structure, valence state and content changes thereby affecting the electrical and magnetic properties of the sample, the test found with increasing the temperature of the substrate, the ZnO film of Co-doped carrier concentration and the PN pattern generator change significantly, while the magnetic properties with the doping concentration was opening downward parabolic shape.

Related Dissertations

CLC: > Industrial Technology > Radio electronics, telecommunications technology > Semiconductor technology > General issues > Material > Compound semiconductor > Oxide semiconductor
© 2012 www.DissertationTopic.Net Mobile