利用自旋發光二極體探討自旋電子經鐵三矽至砷化鎵注入之極化率研究

電子自旋發光二極體是在精確量測電子自旋極化率上一種非常有力的方法。基本原理是透過偵測發光二極體光之圓比率反推回電子自旋極化率。然而，在維持自旋電子極化率是困難的，原因是自旋電子流自鐵磁性材料注入半導體的過程中，極化率勢必受到影響。在二極體之量子井中，極化自旋電子將會與非極化之電洞結合，產生具有圓偏振極化率之光。在這個研究中，我們將著重在具有鐵三矽與砷化鎵異質結構之自旋發光二極體，希望能偵測出鐵三矽之電子自旋極化率。鐵三矽被視為是一種在費米能階上百分之百極化方向之半金屬材料，使鐵三矽可成為高電子極化率注入性材料。在製程上，電子自旋發光二極體是由分子束磊晶技術所成長，量測上是利用低溫磁性光學量測系統，利用低溫高磁場環境來量測光的圓極化率。然而，在數據上已經量測到圓極化率，也證實光的圓極化率是來自於鐵三矽。未來，希望能藉由改變二極體結構以提高光之圓極化率，以確實偵測到鐵三矽之極化率。

關鍵字

自旋電子學；電子自旋發光二極體；鐵三矽；自旋注入；自旋極化率；半金屬；分子束磊晶

並列摘要

The spin-polarized light-emitting diode (spin-LED) is a very powerful means for accurately quantifying spin injection through detecting left and right circular polarized light. It is difficult to maintain the spin polarization injected from a ferromagnetic metal into a semiconductor. The spin polarized electron would combine with un-polarized hole and generate circular polarized light at quantum well. In this work, we have investigated the spin-LEDs made of Fe3Si/GaAs heterostructures. Fe3Si, as a Heusler alloy, is expected to be half metal with 100% spin polarization at the Fermi level, thus making Fe3Si an attractive material for spin injection. The spin-LED was deposited by in-situ multi-chamber MBE system. Furthermore, we have detected the circular polarization by a home-built low temperature measurement system which we set up. In the future, we plan to measure the higher and closer the spin polarization which was generated from Fe3Si.