tailieunhanh - Báo cáo hóa học: " Spin effects in InAs self-assembled quantum dots"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Spin effects in InAs self-assembled quantum dots | dos Santos et al. Nanoscale Research Letters 2011 6 115 http content 6 1 115 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Spin effects in InAs self-assembled quantum dots 1 1 2 3 3 Ednilson C dos Santos Yara Galvão Gobato Maria JSP Brasil David A Taylor Mohamed Henini Abstract We have studied the polarized resolved photoluminescence in an n-type resonant tunneling diode RTD of GaAs AlGaAs which incorporates a layer of InAs self-assembled quantum dots QDs in the center of a GaAs quantum well QW . We have observed that the QD circular polarization degree depends on applied voltage and light intensity. Our results are explained in terms of the tunneling of minority carriers into the QW carrier capture by InAs QDs and bias-controlled density of holes in the QW. Introduction Resonant tunneling diodes RTDs are interesting devices for spintronics because the spin character of the carriers can be voltage selected 1-4 . Furthermore spin properties of semiconductor quantum dots QDs are also of high interest because electron spins can be used as a quantum bit 5 for quantum computing 6 and quantum communication 7 . In this paper we have studied spin polarization of carriers in resonant tunneling diodes with self-assembled InAs QD in the quantum well region. The spin-dependent carrier transport along the structure was investigated by measuring the left-and right-circularly polarized photoluminescence PL intensities from InAs QD and GaAs contact layers as a function of the applied voltage laser intensity and magnetic fields up to 15 T. We have observed that the QD polarization degree depends on bias and light intensity. Our experimental results are explained by the tunneling of minority carriers into the quantum well QW carrier capture into the InAs QDs carrier accumulation in the QW region and partial thermalization of minority carriers. Our devices were grown by molecular beam epitaxy on a n 001 GaAs substrate. The .