高质量稀磁半导体(Ga,Mn)Sb单晶薄膜分子束外延生长

理论预言窄禁带稀磁半导体(Ga,Mn)Sb及其异质结构可能存在量子反常霍尔效应等新奇特性, 近年来受到了特别关注. 但是, 由于(Ga,Mn)Sb薄膜生长窗口窄, 纯相(Ga,Mn)Sb薄膜制备比较困难, 迄今关于这类材料的研究报道为数不多. 本文采用低温分子束外延的方法, 通过优化生长条件, 成功制备出厚度为10 nm, Mn含量在0.016至0.039之间的多组(Ga,Mn)Sb薄膜样品. 生长过程中反射式高能电子衍射原位监测和磁性测量都表明没有MnSb等杂相的偏析, 同时原子力显微镜图像表明其表面形貌平滑, 粗糙度小. 通过生长后退火处理, (Ga,Mn)Sb薄膜的最高居里温度达到30 K. 此外, 本文研究了霍尔电阻和薄膜电阻随磁场的变化关系, 在低温下观测到明显的反常霍尔效应.

Molecular-beam epitaxy of high-quality diluted magnetic semiconductor (Ga,Mn)Sb single-crystalline films

Diluted magnetic semiconductor (Ga, Mn)Sb and its related hetero-structures have attracted much attention in recent years since they are predicted to have some novel properties, such as the quantum anomalous Hall effect etc. However, it is not easy to grow high-quality (Ga, Mn)Sb films due to their narrow growth window. In this article, a series of 10 nm thick (Ga, Mn)Sb films with different Mn contents from 0.016 to 0.039 have been grown by molecular-beam epitaxy at low temperaturs (～230 ℃). The films have high crystalline quality as confirmed by in situ reflection high-energy electron diffraction and ex situ atomic force microscopy, and no MnSb phase could be observed. Curie temperature up to 30 K has been obtained in one (Ga, Mn)Sb film after post-growth thermal annealing. The magneto-resistance and anomalous Hall effect of this film have also been investigated at different temperatures.