A study of electron and spin state of magnetic thin layer grown on negative electron affinity semiconductor

我们试图研究负电子亲和势半导体表面上生长的铁磁层(和/或多层膜)的表面材料(如铁、镍)及其厚度对电子和自旋态的影响以及费米能级的变化。首先通过安装离子泵对MBE真空室的抽运功率进行了改造，然后对样品处理系统进行了改造。在达到良好的真空条件后，我们生长了几种类型的样品，包括铁和/或Dy及其与砷化镓的化合物。在生长过程中，我们用反射式高能电子衍射仪(RHEED)监测了样品的表面状况，并在生长后对一半的样品进行了X射线衍射(XRD)和透射电子显微镜(TEM)的检测。(这些工作的一部分已经发表)对于其余的样品，我们选择了无定形砷帽，以保持表面的状况，即使在取出真空室后也是如此。为了研究表面电子态和费米能级，我们利用佐贺光中心(Tosu)同步辐射装置上的几个光子能量的光电子能谱。这些样本的光谱分析正在进行中。通过这项工作，我们建立了一种简单可靠的在MBE小室中封顶砷的方法，并通过光电子能谱进行了验证，因为我们可以看到热去盖层去除砷盖层后表面清洁的证据。

We tried to investigate electron and spin state, and changing of Fermi level concerning to surface material (for example iron, nickel) and its thickness of ferro-magnetic layer (and/or multi layer), that are grown on semiconductor surface of negative electron affinity (NEA). At first we modified the pumping power of a MBE vacuum chamber by installing ion-pump, and then modified the sample manipulation system. After achieving a good vacuum condition we grew several types of samples with iron and/or Dy and its compound with gallium-arsenide. During the growth we monitored the surface condition with the reflection high electron energy diffraction (RHEED) and after the growth half of samples were checked the x-ray diffraction (XRD) and the transmission electron microscope (TEM). (A part of these work were published) For the rest of samples, we chose amorphous arsenic cap to keep the condition of the surface even after taking out of the vacuum chamber. To investigate the surface electron state and Fermi level, we employed the photoelectron spectroscopy with several photon energy from synchrotron radiation facility in Tosu (Saga Light Centre). Spectrum analysis from these samples is undergoing. Through this work, we established an easy and reliable method of arsenic capping in the MBE chamber, that were also checked by photoelectron spectroscopy because we could see clear evidence of clean surface after removing the arsenic capping layer by heat decapping.