First-Principles Study On Fe, Co Doped ZnO-Based Diluted Magnetic Semiconductors

Using the charge attribute and the spin attribute of electrons, the spintronics devices will greatly promote the speed of processing and transporting information, and expand the capacity of information storage. Zn O diluted magnetic semiconductors have a wide range of applications in the field of the spintronics devices. Therefore, the research of Zn O diluted magnetic semiconductor has become the focus of researchers’ attention. So far, Zn O diluted magnetic semiconductors have been done a lot of research both in theory and in experiments. And it has made great progress. However, there are many problems should be resolved. For example, the results of the study are not unified, the experimental repetition rate is poor, the origin of magnetic mechanism is controversial and Curie temperature is too low. All these problems restrict the development and application of diluted magnetic semiconductors. Meanwhile, Zn O has excellent performances in optical properties. So, its optical properties should be studied at the same time. The main contents and results of this paper are as follows:(1) After constructing models of Fe doped Zn O and Co doped Zn O, the magnetic properties and electronic structure of them are calculated and analyzed. The results show that without other impurity elements or defects, Fe-doped Zn O and Co-doped Zn O don’t have the room temperature ferromagnetism. The magnetic stability of Co doped Zn O is associated with the relative position of dopant atoms, while Fe doped Zn O is antiferromagnetic state. To enable Fe doped Zn O and Co doped Zn O can be applied in actual, they must be modified by other means to make they have the room temperature ferromagnetism. Those carriers which are formed by redundant electrons play an important regulatory role in the ferromagnetic state of them. Therefore, increasing the concentration of redundant carriers could be considered to make them have the room temperature ferromagnetism.(2) On the basis of the models of Fe doped Zn O and Co doped Zn O, the models of Fe-In co-doped Zn O and Co-In co-doped Zn O are constructed. Then, the magnetic property and electronic structure of them are calculated and analyzed. The results show that Fe-In co-doped Zn O and Co-In co-doped Zn O have the room temperature ferromagnetism. And the room temperature ferromagnetism of Co-In co-doped Zn O is stronger than that of Co-In co-doped Zn O. For their regulation mechanism, it can be explained by double exchange mechanism which is regulated by redundant carriers. Those redundant carriers are free electrons.(3) At last, the optical properties of those models built in this paper are calculated and analyzed. The results show that compared to the intrinsic Zn O, their optical properties have obvious changes. Firstly, although the absorption spectra of them are still mainly distributed in ultraviolet area, their absorptive capacity is obviously superior to the intrinsic Zn O. Secondly, in the visible area(the low energy: 1.61 e V to 3.10 e V), they have obvious absorption peak, while the absorption coefficient of intrinsic Zn O is almost zero. Moreover, the absorptive capacity of co-doped Zn O is better than single doped Zn O. Therefore, they have good application potential in the field of ultraviolet and visible light electronic devices. At the same time, this potential of co-doped Zn O is greater than that of single doped Zn O, and this potential of Fe-In co-doped Zn O is greater than that of Co-In co-doped Zn O.