Fabrication and characterization of GaAs quantum well buried in AlGaAs/GaAs heterostructure nanowires

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We developed a growth method for forming a GaAs quantum well contained in an AlGaAs/GaAs heterostructure nanowire by using selective-area metal organic vapor phase epitaxy. To find the optimum growth condition of AlGaAs nanowires, we changed the growth temperature between 800 and 850℃ and found that best uniformity of the shape and the size was obtained near 800℃ but lateral growth of AlGaAs became larger, which resulted in a wide GaAs quantum well grown on the top (111)B facet of the AlGaAs nanowire. To form the GaAs quantum well with a reduced lateral size atop the AlGaAs nanowire, a GaAs core nanowire about 100 nm in diameter was grown before the AlGaAs growth, which reduced the lateral size of AlGaAs to roughly half compared with that without the GaAs core. Photoluminescence measurement at 4.2 K indicated spectral peaks of the GaAs quantum wells about 60 meV higher than the acceptor-related recombination emission peak of GaAs near 1.5 eV. The photoluminescence peak energy showed a blue shift of about 15 meV, from 1.546 to 1.560 eV, as the growth time of the GaAs quantum well was decreased from 8 to 3 sec. Transmission electron microscopy and energy dispersive X-ray analysis of an AlGaAs/GaAs heterostructure nanowire indicated a GaAs quantum well with a thickness of 5-20 nm buried along the <111> direction between the AlGaAs shells, showing a successful fabncation of the GaAs quantum well.
2010-12-01