Study of Room-temperature Spin Injection in Ni80Fe20/AlOx/GaAs-based QW (MIS Spin-LED) System

Abstract

Many researchers have been looking for the way to fabricate new devices by integrating metal-based electronics with present semiconductor technology. Since Datta et al. [3] proposed the idea of ‘spin-based’ field-effect transistor (Spin-FET) in 1990, much of effort was exhausted in the realization of spin-FET because it adds additional spin-degree of freedom in conventional ‘charge-based’ field-effect transistor. One might wonder how Spin-FET devices can work at all instead of a large conductivity mismatch between ferromagnetic metal and semiconductor. One solution is to employ a tunnel barrier to inject a spin-polarized current. However, no report has addressed a successful Spin-FET device yet. This study is to follow spin-FET dream and, at the very beginning, we focus our research on design and fabrication of a spin injection source using ferromagnetic metal with tunnel barrier. For integration of ferromagnetic metal and semiconductor, surface oxides on GaAs substrate were removed effectively by using atomic hydrogen. To measure spin injection efficiency for the injection source, we also designed and calculated quantum well (QW) structure for detection of spin-polarized current. However, there is no available measurement apparatus in NTU yet, and so we put much of our effort on the study of design and fabrication of a theoretically high spin injection source.