Thermal annealing of defects in InGaAs/GaAs heterostructures with three-dimensional islands

International audienceA report is presented on the investigation of the influence of in situ annealing of the InGaAs layer in p-n InGaAs/GaAs structures grown by the metalloorganic chemical vapor deposition upon the formation of coherently strained three-dimensional islands. The structures were studied by the methods of capacitance-voltage measurements, deep-level transient spectroscopy, transmission electron microscopy, and photoluminescence. It is established that three-dimensional islands with misfit dislocations are formed in the unannealed structure A, while quantum dots are formed in the annealed structure B. The deep-level defects were investigated. In structure A, defects of various types (EL2, EL3 (I3), I2, HL3, HS2, and H5) are present in the electron-accumulation layer. Concentrations of these traps are comparable to the shallow donor concentration, and the number of hole traps is higher than that of the electron traps. On the in situ annealing, the EL2 and EL3 defects, which are related to the formation of dislocations, disappear, and concentrations of the other defects decrease by an order of magnitude or more. For structure A, it is established that the population of the quantum states in the islands is controlled by the deep-level defects. In structure B, the effect of the Coulomb interaction of the charge carriers localized in the quantum dot with the ionized defects is observed

InGaAs nanodomains formed in situ on the surface of (Al,Ga)As

International audienceA new method for obtaining InGaAs nanodomains on the surface of GaAs or (Al,Ga)As is suggested. At the first stage, an InGaAs layer with a thickness above the critical value for dislocation formation is deposited onto the substrate surface by metalorganic CVD. Then the InGaAs film is coated with a thin AlAs layer and annealed at an elevated temperature. The “repulsion” of AlAs from plastically relaxed regions near dislocations and the high temperature stability of AlAs result in that evaporation is restricted to the regions containing defects. The self-organization effects favor the formation of an ordered array of coherent nanodomains that can be used for obtaining buried low-dimensional nanostructures and/or nanoheteroepitaxial inclusions

Formation of defect-free InGaAs-GaAs quantum dots for 1.3 ?m spectral range grown by metal-organic chemical vapor deposition

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