Growth of mirror-like Zn 1-x Mn x O diluted magnetic semiconductor thin films by r.f. magnetron sputtering method

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Growth of mirror-like Zn1-xMnxO diluted magnetic semiconductor thin films by r.f. magnetron sputtering method

Sejoon Lee1, Hye Sung Lee1, and Deuk Young Kim1* 1 Quantum-functional Semiconductor Research Center, Dongguk University 3-26 Phil-dong, Chung-gu, Seoul 100-715, KOREA ABSTRACT The Zn1-xMnxO thin films were grown on Al2O3 (0001) substrates by an r.f. magnetron sputtering method. The film grown with employing buffer layer shows mirror-like surface, while the film grown without buffer layer shows the columnar-structured configuration. The mirrorlike Zn0.93Mn0.07O thin films have the single crystalline phase with (000ℓ) orientation normal to the substrate surface and show the UV emission originated from the near band-edge-emission for the measurements of x-ray diffraction and photoluminescence, respectively. The mirror-like Zn0.93Mn0.07O film clearly showed a hysteresis loop, which is obvious evidence of ferromagnetism, and the Curie temperature was determined to be 68 K for the characterization of the temperature-dependent magnetization.

INTRODUCTION Diluted magnetic semiconductors (DMSs) are most favorable materials for spintronic device applications, on account of providing new functionality for the semiconductor devices using both charge and spin degree of the freedom [1-2]. Possible spintronic devices are spinvalve transistors, spin light-emitting diodes, non-volatile storage and logic devices, and solar sells [3-5]. For the realization of those applications, the DMSs should show characteristics of ferromagnetism with the high Curie temperature (TC) as well as the single crystalline phase. In addition, the formation of high quality diluted magnetic semiconductor (DMS) thin films is an important issue because heteroepitaxial films are required for applications of sophisticated spintronic devices. Since Dietl predicted that the Mn-doped ZnO would show the ferromagnetic behavior with the TC of 300 K [6], great deal of studies on the Zn1-xMnxO DMSs have been progressed. Recently, Norton [7] produced the Mn-implanted ZnO:Sn single crystal with the TC of 250 K. However, Mn-implanted ZnO:Sn DMSs are not the thin film but just bulk single crystal even though they have fairly high TC. In association with a study on ferromagnetic Zn1-xMnxO thin films, the report on high quality Zn1-xMnxO thin films with high TC ferromagnetism is still poor, *

Corresponding Author. E-mail Address: [email protected]

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although a few studies [8-9] have been reported. Thus the study on the growth and the characterization of Zn1-xMnxO thin film is keenly required to realize the spintronic device applications. In this paper, we report on material properties of mirror-like Zn1-xMnxO thin films grown by the r.f. magnetron sputtering deposition.

EXPERIMETAL DETAILS Zn1-xMnxO thin films were grown on Al2O3 (0001) substrates using the r.f. magnetron sputtering deposition method. The sputtering target of Zn1-xMnxO (Mn: 5 wt%) used in this work was made using a standard ceramic synthesis method. In our growth process, the mixt

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