Growth Dynamics and Properties of Compound Semiconductor Layers Prepared by Low Temperature Molecular Beam Epitaxy

低温分子束外延制备化合物半导体层的生长动力学和性能

基本信息

批准号：
10450002
负责人：
OHNO Hideo
金额：
$ 8.77万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

III-V semiconductors and/or diluted magnetic semiconductors, and their nanostructures were grown by low-temperature (LT-) molecular beam epitaxy (MBE). The growth dynamics and structures have been investigated by reflection high energy electron diffraction (RHEED), and atomic force (AFM) and/or magnetic force (MFM) microscopy. Their optical, magnetic, and transport properties of the samples were also characterized.The summary of the research results are :1. It has been observed that the oscillation of the RHEED intensity recovers as the growth temperature was much lowered (〜300℃). The experimental results of the temperature dependence were successfully represented by Monte-Carlo simulation calculation based on the model which treats the excess arsenic as self-surfactant.2. A new diluted magnetic semiconductor (Ga,Mn)Sb with a few percent Mn concentration has been successfully grown by MBE. The dependence of their properties on the growth temperature was investigated by AFM/MFM, magneti … More zation and magnetotransport measurements. By AFM and MFM observations, it was found that MnSb clusters were formed on the surface. When the growth temperature is as high as 〜560℃, the sample is ferromagnetic at room temperature, and the MnSb clusters dominate the whole magnetization properties. On the other hand, the magnetization and magnetotransport properties of the samples grown at LT exhibit another magnetic phase below 20 K, indicating the existence of (Ga,Mn)As which becomes ferromagnetic at lower temperatures (〜20 K).3. It has been demonstrated that size uniformity of the self-assembled InMnAs quantum dots grown on (211)B GaAs substrate can be improved by introducing Mn, indicating that Mn plays a role of surfactant.4. All-semiconductor ferromagnet (GaMn)As/nonmagnet (Al,Ga)As/ferromagnet (Ga,Mn)As trilayer structures were fabricated by LT-MBE, and their magnetic and transport properties were characterized. It has been demonstrated that the magnetic coupling between two ferromagnetic layers can be controlled by tuning the thickness and/or the barrier hight of the non-magnetic layer. Furthermore, we have observed the giant magnetoresistance effect in this system for the first time. Less

III-V 半导体和/或稀释磁性半导体及其纳米结构通过低温 (LT-) 分子束外延 (MBE) 生长，并通过反射高能电子衍射 (RHEED) 研究了生长动力学和结构。原子力（AFM）和/或磁力（MFM）显微镜也表征了它们的光学、磁性和输运特性。研究结果总结如下： 1．当生长温度大大降低（~300℃）时，RHEED强度的振荡恢复。基于将过量砷视为自表面活性剂的模型，通过蒙特卡罗模拟计算成功地表达了温度依赖性的实验结果。2。一种具有百分之几Mn浓度的新型稀释磁性半导体(Ga,Mn)Sb已通过MBE成功生长，并通过AFM/MFM研究了其性能对生长温度的依赖性。通过AFM和MFM观察发现，当生长温度高达~560℃时，样品在室温下呈铁磁性，且MnSb团簇。另一方面，LT 生长的样品的磁化和磁输运特性表现出低于 20 K 的另一个磁相，表明存在(Ga,Mn)As 在较低温度 (~20 K) 下变成铁磁体。3. 已经证明，通过引入 Mn，可以改善在 (211)B GaAs 衬底上生长的自组装 InMnAs 量子点的尺寸均匀性。表明Mn起到了表面活性剂的作用。4． (Ga,Mn)As 三层结构是通过 LT-MBE 制备的，并且表征了它们的磁性和传输特性，已经证明可以通过调节铁磁层的厚度和/或势垒高度来控制两个铁磁层之间的磁耦合。此外，我们首次在该系统中观察到巨磁阻效应。