热退火对Mn离子注入非故意掺杂GaN微结构、光学及磁学特性的影响

Influences of post-heat treatment on microstructures,optical and magnetic properties of unintentionally doped GaN epilayers implanted with Mn ions

通过Mn离子注入非故意掺杂GaN外延层制备了GaN:Mn薄膜,并研究了退火温度对GaN:Mn薄膜的微结构、光学及磁学特性的影响.对不同退火温度处理后的GaN:Mn薄膜的拉曼谱测试显示,出现了由与离子注入相关的缺陷的局域振动(LV)和(Ga,Mn)N中Mn离子的LV引起的新的声子模.在GaN:Mn薄膜的光致发光谱中观察到位于2.16,2.53和2.92 eV处的三个新发光峰(带),其中位于2.16 eV处的新发光带不能排除来自Mn相关辐射复合的贡献.对GaN:Mn薄膜的霍尔测试显示,退火处理后样品表现出n型体材料特征.对GaN:Mn薄膜的振动样品磁强计测试显示,GaN:Mn薄膜具有室温铁磁性,其强弱受Mn相关杂质带中参与调节磁相互作用的空穴浓度的影响.

In this study, GaN ： Mn thin films are fabricated by implementing Mn ions into the undoped CaN material. The effects of annealing temperature on microstructures, optical and magnetic properties of the thin films are investigated. The Raman spectra measured from Mn-implanted GaN samples at different annealing temperatures show that new phonon modes, which are related to macroscopic disorder or vacancy-related defects caused by Mn-ion implantation and the local vibrational mode of Mn atoms in the （Ca, Mn）N, are created. The results of photoluminescence measurement show that new peaks appear at 2.16, 2.53, and 2.92 eV. Among these, the new emission around 2.16 eV, besides some contributions from optical transitions from the conduction band or shallow donor to a deep acceptor, cannot exclude the contribution from optical transitions of free electrons in the conduction band to Mn acceptor level. The Hall test shows that the annealed samples are of n type. Ferromagnetism is observed in the Mn doped GaN thin film at 300 K and found to be sensitive to the density of holes that mediate the Mn-Mn magnetic exchange interaction in this Mn-related impurity band.