Extremely low density InAs quantum dots （QDs） are grown by molecular beam droplet epitaxy. The gallium deposition amount is optimized to saturate exactly the excess arsenic atoms present on the GaAs substrate surfac...Extremely low density InAs quantum dots （QDs） are grown by molecular beam droplet epitaxy. The gallium deposition amount is optimized to saturate exactly the excess arsenic atoms present on the GaAs substrate surface during growth, and low density InAs/GaAs QDs （4× 10^6 cm^-2） are formed by depositing 0.65 monolayers （MLs） of indium. This is much less than the critical deposition thickness （1.7 ML）, which is necessary to form InAs/GaAs QDs with the conventional Stranski-Krastanov growth mode. The narrow photoluminescence linewidth of about 24 meV is insensitive to cryostat temperatures from IO K to 250K. All measurements indicate that there is no wetting layer connecting the QDs.展开更多
We have studied the morphology evolution of holed nanostructures formed by aluminum droplet epitaxy on a GaAs surface.Unique outer rings with concentric inner holed rings were observed.Further,an empirical equation to...We have studied the morphology evolution of holed nanostructures formed by aluminum droplet epitaxy on a GaAs surface.Unique outer rings with concentric inner holed rings were observed.Further,an empirical equation to describe the size distribution of the outer rings in the holed nanostructures has been established.The contour line generated by the equation provides physical insights into quantum ring formation by droplets of groupⅢmaterials onⅢ-Ⅴsubstrates.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 60625405, the Special Fund for Major State Basic Research Project, and the National High Technology Research and Development Programme of China.
文摘Extremely low density InAs quantum dots （QDs） are grown by molecular beam droplet epitaxy. The gallium deposition amount is optimized to saturate exactly the excess arsenic atoms present on the GaAs substrate surface during growth, and low density InAs/GaAs QDs （4× 10^6 cm^-2） are formed by depositing 0.65 monolayers （MLs） of indium. This is much less than the critical deposition thickness （1.7 ML）, which is necessary to form InAs/GaAs QDs with the conventional Stranski-Krastanov growth mode. The narrow photoluminescence linewidth of about 24 meV is insensitive to cryostat temperatures from IO K to 250K. All measurements indicate that there is no wetting layer connecting the QDs.
基金The authors gratefully acknowledge the financial support by the MRSEC Program of NSF Grant(DMR-0520550).
文摘We have studied the morphology evolution of holed nanostructures formed by aluminum droplet epitaxy on a GaAs surface.Unique outer rings with concentric inner holed rings were observed.Further,an empirical equation to describe the size distribution of the outer rings in the holed nanostructures has been established.The contour line generated by the equation provides physical insights into quantum ring formation by droplets of groupⅢmaterials onⅢ-Ⅴsubstrates.
