| Recently, the semiconductor industry there is an uninterrupted evolution towards higher and higher integration which results in capability increase of devices and dimension reduction of elements. Hence, more and more researchers pay attention to meet the proposed higher requirements for preparation and performance of the multifunctional materials. As a kind of multifunctional materials, P-type oxide-based DMSs exhibit unique magnetic, magneto-electrical and magneto-optical effects as well as high transparency in the visible region. Therefore, they can be used in spintronic devices and transparent optoelectronic devices. What’s more, theoretical predictions pointed out that ferromagnetic coupling between magnetic ions could be formed more easily in p-type semiconductors due to hole carriers serving as a medium.Among the P-type transparent conducting oxide (TCO), CuCrO2delafossite with the ABO2structure, which have the highest conductivity (σ=220S cm-1), is considered as an excellent candidate for the matrix to prepare p-type oxide-based DMSs. The first part in the paper is about Mn doping CuCrO2thin films by Pulsed Laser Deposition (PLD). We study systematically the films’crystal structure, ions valence, electrical, optical and magnetic properties through the variation of deposition conditions and doping concentration. And we investigate the conductive mechanism, the variation of optical structure mechanism, and the origin of magnetism mechanism. The main results are as follows:thin films is crystallized in single3R-CuCrO2delafossite structure with a c-axis quasi-epitaxial orientation, and that Mn3+and Mn4+substitute Cr3+in B site. On the electrical property, the process of PLD is benefit for insertion of the interstitial oxygen, and lead to obtain a higher hole density. On the another hand, the coexistence of Mn3+and Mn4+induces the hole-mediated Mn3+-Mn4+and Mn3+-Cr3+double exchange (DE) interactions and lead the increasing of carrier mobility. Therefore, the conductivity is about three orders of magnitude higher than Cu(Cr1-xMnx)O2film prepared by chemical solution deposition. On the optical property, films have a relatively high transmittance in the visible region. At the wavelength of750nm, the highest transmittance is70%and is5%higher than Cu(Cr1-xMnx)O2film prepared by chemical solution deposition. The variations of optical transmittance, the direct optical band gap and hole density all exhibit the same trend with the increasing Mn content and this phenomenon is accord with the Burstein-Moss shift. The hole-mediated Mn3+-Mn4+and Mn3+-Cr3+DE interactions bring films the ferromagnetic order with Tc near room temperature, and Tc can reach285K. With the Mn addition, the numbers of the Mn3+-Mn4+and Mn3+-Cr3+pairs are increased and the Ms and Tc are gradually enhanced.The research point out that the P-type conductivity of Cu(Cr0.95Mg0.05)O2is higher than CuCrO2. Therefore, the second part in the paper is about Fe/Mg doping B site in CuCrO2thin films by Sol-Gel method. Under the Mg concentration of5at%, we study systematically the films’crystal structure, ions valence, electrical, optical and magnetic properties by change Mn doping concentration. And we investigate the conductive mechanism, the variation of optical structure mechanism, and the origin of magnetism mechanism. The main results:Cu(Cr0.95-xFexMg0.05)O2thin films is crystallized in a single3R-CuCrO2delafossite structure with a c-axis quasi-epitaxial orientation. Fe3+and Mg2+substitute Cr3+in B site, Cu+co-exist with Cu2+in A site. On the electrical property, with the increasing of Fe doping concentration, the numbers of Cu2+ions decreases and the hole concentration gradually increases. On the another hand, Fe3+ions substituting Cr3+ions will enhance the degree of lattice distortion and thus strengthen the carrier scattering. Under the above two influence, the conductivity of Cu(Cr0.95-xFexMg0.05)O2thin films is gradually increases. On the optical property, Cu(Cr0.95-xFexMg0.05)O2thin films prepared by Sol-Gel have a relatively high transmittance in the visible region. At the wavelength of750nm, the transmittance is about50～60%and is about20～30% higher than Cu(Cr0.95Mg0.05)O2film prepared by Sputtering. On the magnetic property, the hole-mediated Fe3+-Fe3+super exchange (SE) interactions bring films the room temperature ferromagnetic order. With the increasing of Fe doping concentration, the numbers of Fe3+-Fe3+pairs are accordingly increased. At the same time, the hole concentration gradually adds and the Ms enhanced.In summary, Cu(Cr1-xMnx)O2films prepared by PLD exhibit a relatively balanced electrical, optical, and magnetic properties. Especially, the thin film has the highest electrical conductivity, saturation magnetization, Curie temperature and transmittance in the range of visible light. Cu(Cr0.95-xFexMg0.05)O2thin films prepared by Sol-Gel also have relatively higher transmittance and room temperature ferromagnetic order. As a new kind of P-type transparent DMSs materials, these research data of above experiments will provide a reference for the development of multifunction devices. |
PDF Full Text Request