Self-alignment of InGaAs quantum dots was achieved by growing the quantum dots on the multiatomic steps in metalorganic chemical vapor deposition. In this technique, first GaAs epilayer with multiatomic step structures along straight lines was grown on a vicinal GaAs substrate under appropriate growth conditions. Then, the InGaAs quantum dots were grown selectively on the multiatomic step edges using strain effects. This growth technique results in spontaneously aligned InGaAs quantum dots without any preprocessing technique prior to the growth.
We report the observation of resonant edge excitations of a high-mobility two-dimensional electron system in the regime of the fractional quantum Hal1 effect. Narrow edge resonances are observed only on fractional or integer Hall plateaus and have a resonance frequency proportional to the quantized Hall conductivity.We interpret our results using a theory of edge magnetoplasmons in the quantum Hall regime. Resonant edge excitations of a bounded two-dimensional electron system (2D ES) in a perpendicular magnetic field 8, edge magnetoplasmons (EMP's), are modes with wavelengths defined by the sample perimeter. First studies by Allen, Stormer, and Hwang ' withGaAs/Al"Gal -"As heterojunctions and by Mast, Dahm, and Fetter on the surface of liquid helium have stimulated a large body of experimental' and theoretical work. ' ' Experimentally, systems have been investigated with sizes that differ by many orders of magnitudes.
We report the direct deposition of strained InGaAs-dot structures with a diameter of about 15 nm on GaAs surfaces by metalorganic chemical vapor deposition growth. High resolution scanning electron micrographs show highly uniform quantum-sized dots formed by the Stranski–Krastanow growth mode. The sharp photoluminescence emission band of buried dot structures indicates efficient carrier capture and a homogeneous heterointerface. The average dot size and area dot density can be controlled accurately by growth temperature, and InGaAs deposition thickness, respectively.
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