Abstract
We demonstrate experimentally the submicron size self-assembled (SA) GaAs quantum rings (QRs) by quantum size effect (QSE). An ultrathin In0.1 Ga0.9As layer with different thickness is deposited on the GaAs to modulate the surface nucleus diffusion barrier, and then the SA QRs are grown. It is found that the density of QRs is affected significantly by the thickness of inserted In0.1 Ga0.9As, and the diffusion barrier modulation reflects mainly on the first five monolayer . The physical mechanism behind is discussed. The further analysis shows that about 160 meV decrease in diffusion barrier can be achieved, which allows the SA QRs with density of as low as one QR per 6 μm2. Finally, the QRs with diameters of 438 nm and outer diameters of 736 nm are fabricated using QSE.
Highlights
Quantum rings (QRs), being viewed as the artificial benzene analogs, have attracted the increasing interests due to their novel magnetic and optoelectronic properties[1,2,3,4] and the potential applications as high performance THz detectors [5,6], solar cells [7], lasers [8], and single photon sources [9]
We demonstrated the submicron size GaAs QRs by modulating the surface energy, which were achieved by the quantum size effect (QSE) of InGaAs nanolayer
This extremely low density can be beneficial for the fabrication of single QR device as well as single quantum dot (QD) device because the similar droplet epitaxy approach is used to fabricate the QDs [4]
Summary
Quantum rings (QRs), being viewed as the artificial benzene analogs, have attracted the increasing interests due to their novel magnetic and optoelectronic properties[1,2,3,4] and the potential applications as high performance THz detectors [5,6], solar cells [7], lasers [8], and single photon sources [9]. Manipulate atoms to control the size and shape of QRs are strongly pursued. The conventional approaches including the different growth temperature [10], the annealing time [11], the arsenic pressure used in the annealing [12], and partially capping growth [13] had been applied to fabricate the different shape selfassembled (SA) QRs. there are few investigations from the surface energy or diffusion barriers point of view which affects the atom diffusion from the well-known Arrhenius relation of diffusion coefficient. Surface energy and diffusion barriers had been demonstrated to be sensitive to the thickness of ultrathin epitaxy layer on the surface [14,15,16,17] due to the quantum size
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