| Summary: | 碩士 === 國立臺北科技大學 === 光電工程系研究所 === 98 === Diluted magnetic semiconductors can utilize charge and spin degrees of freedom of a single device and could be applied to the spintronics. By virtue of the wide-bandgap characteristic of ZnO and the large magnetic moment of Co in ZnO, Co-doped ZnO material is ideal for fabricating the diluted magnetic semiconductor.
By using the instruments like XRD, SEM, and SQUID, we can examine the crystal structure, the surface morphology, and the magnetic behaviors of the deposited thin film respectively. We observed that as the grain size decreases, the measured hysteresis loop has more obvious remanance and coercivity. The phenomenon may be due to the richer oxygen vacancies of the sample with smaller grain size and can be illustrated by the bound magnetic polaron model.
If we annealed the as-deposited ZnCoO thin film under the pressure of 45 mtorr, the resulted sample would display higher remanence and larger saturated magnetization. We infer that the improvement is due to the higher dielectric constant and lower d-spacing of the (103) crystal plane when compared with the (002) one.
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