Fabrication of Semiconductor Spin Device -Integration of Spin Transistor and Quantum Dots -

点击翻译按钮获取中文摘要

Spin injection from ferromagnet into semiconductor has been investigated and high efficiency spin injection was verified. We have also confirmed the spin transistor operation based on the spin injection technique in Fe/InAs hybrid structure. Itemized research results are listed below.(1)Circular polarization measurements of electroluminescence from Fe/InAs spin diode revealed that the degree of circular polarization of 18-20% and spin injection efficiency of 36-40% is possible.(2)Surface reaction at the Fe/InAs interface has been investigated using Secondary Ion Mass Spectroscopy (SIMS), Transmission Electron Microscopy (TEM) and Reflection High Energy Electron Diffraction (RHEED) during the MBE growth comparing two samples grown at 23℃ and at 175℃. Cross diffusion was observed at the interface in 175℃ sample but not in 23℃ sample. TEM showed atomically abrupt interface in both samples in large part of the region. Although one or two mono-atomic layers of unknown structure were observed in some places, interface reaction was not so clear. RHEED study revealed more island formation of Fe at the initial stage of the Fe growth in 23℃ sample. Lower temperature growth was shown to maintain better interface for better luminescence and spin injection properties.(3)Based on the basic spin injection study in Fe/InAs hybrid system, we have confirmed the spin transistor operation by observing the gate controlled current oscillation in high indiun content InGaAs channel clad by InAlAs barrier layers lattice matched to InP substrate. This is the first observation of spin transistor operation.