Investigation of structure and magnetic characteristics of Ni-implanted AlGaN films
Investigation of structure and magnetic characteristics of Ni-implanted AlGaN films
复制标题
Ni注入AlGaN薄膜的结构和磁特性研究
DOI：
10.1007/s11082-017-0942-6
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发表时间：
2017
影响因子：
3
通讯作者：
Chen Changqing
中科院分区：
文献类型：
--
作者：
Zhao Chong;Wan Qixin;Dai Jiangnan;Zhang Jun;Wu Feng;Wang Shuai;Long Hanling;Chen Jingwen;Chen Changqing
The structural, valence of elements and magnetic characteristics of Ni-implanted Al0.5Ga0.5N films, deposited on Al2O3substrates by metalorganic chemical vapor deposition (MOCVD), were reported. Ni ions were implanted into Al0.5Ga0.5N films by Metal Vapor Arc (MEVVA) sources under the energy of 100 keV for 3 h. The films were annealed at 900 K in the furnace for the transference of Ni ions from interstitial sites to substitutional sites in AlGaN and activating the Ni3+ions. Characterizations were carried out in situ using X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and Vibrating sample magnetometer (VSM), indicating that the films have wurtzite structure without forming a secondary phase after annealing. Ni ions were successfully implanted into substitutional sites of Al0.5Ga0.5N films and the chemical bonding states of Ni3+is Ni–N. The apparent hysteresis loops prove the films exhibited ferromagnetism at 300 K. The room temperature (RT) Msand Hcobtained were approximately 0.22 emu/g and 32.97 Oe, respectively. From the first-principles calculation, A total magnetic moment of 2.86 μB per supercell is calculated: the local magnetic moment of NiN4tetrahedron, 2.38 μB, makes the primary contribution. The doped Ni atom hybridizes with its four nearby N atoms in NiN4tetrahedron, then N atoms are spin polarized and couple with Ni atom with strong magnetization, which result in ferromagnetism. Therefore, the p-d exchange mechanism is responsible for ferromagnetism in Ni-doped AlGaN. It is expected that the room temperature ferromagnetic Ni-doped Al0.5Ga0.5N films can make it possible to the applications for the spin electric devices.
