Small linewidth and short lifetime of emission from GaAs/AlAs core/shell quantum dots on the facet of GaAs nanowire

摘要

Inspired by the novel quantum dot (QD) structure, GaAs/AlAs core/shell QD on the facet of GaAs/AlGaAs nanowire (NW), and its nice single-photon emission properties in Heiss et al's work (2013 Nature Mater. 12 439), a mechanism of wavefunction resonance in QD, induced by the AlAs shell surrounding QD, is proposed and proved by Schr?dinger equation simulation. The thin AlAs shell between GaAs NW and QD, acting as a tunnelling barrier, determines QD emission linewidth. A 3 nm thick AlAs shell gives a linewidth of 35 μeV. QD emission efficiency and lifetime are studied by rate equations. The parallel decay channel along continuous GaAs NW band, in rate of Γ_R, reduces QD emission lifetime. For ΓR = 1 × 10~9 s ~(-1) and 3 nm thick AlAs shell, the lifetime is 680 ps. The AlAs shell thickness shows opposite influences on QD spectral linewidth and emission efficiency, and thus must be traded off.