Large size self-assembled quantum rings: quantum size effect and modulation on the surface diffusion
1 State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, China
2 School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, 639798, Singapore
Nanoscale Research Letters 2012, 7:520 doi:10.1186/1556-276X-7-520Published: 24 September 2012
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.