Growth and Characterization of GaDyN/AlGaN Multi-Quantum Well Structures

Abstract

GaDyN single layer and GaDyN/AlGaN multi-quantum well (MQW) structures are grown on GaN templates by radio-frequency plasma-assisted molecular-beam epitaxy (RF-MBE). X-ray diffraction θ/2θ scan curves exhibited well-defined satellite peaks for the MQW structure samples. From analyzing extended x-ray absorption fine structure (EXAFS), majority of Dy atoms are found to be incorporated into substituting the Ga sites in the GaDyN with wurtzite structure, which has longer bond length than that of GaN. The lattice constant of the GaDyN is larger than that of GaN due to large radius of Dy ion. Two photoluminescence excitation bands are found at 342 and 581 nm, which are identified as the band-to-band transition in the GaDyN quantum wells and the inner-4f transition of Dy 3+ ions, respectively. Ferromagnetism is confirmed in the magnetization versus magnetic field curves at 10 and 300 K for the both structure samples. It is found that the MQW sample has larger magnetic moment than the single layer sample. This enhancement of magnetic moment is realized due to a strong exchange interaction between confined electrons and Dy ions.