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Unique electronic properties of semiconductor heterostructured nanowires make them useful for future nano-electronic devices. Here, we present a study of the band bending effect at the heterointerface of GaAs/InAs core/shell nanowires by means of synchrotron based X-ray photoelectron spectroscopy. Different Ga, In, and As core-levels of the nanowire constituents have been monitored prior to and after cleaning from native oxides. The cleaning process mainly affected the Asoxides and was accompanied by an energy shift of the core-level spectra towards lower binding energy, suggesting that the As-oxides turn the nanowire surfaces to n-type. After cleaning, both As and Ga core-levels revealed an energy shift of about -0.3 eV for core/shell compared to core reference nanowires. With respect to depth dependence and in agreement with calculated strain distribution and electron quantum confinement, the observed energy shift is interpreted by band bending of core-levels at the heterointerface between the GaAs nanowire core and the InAs shell. [ABSTRACT FROM AUTHOR]

Scanning electron microscopic and X-ray diffraction studies of Cu(II) oxide films, deposited by oxidizing gas source and pulsed laser ablation on MgO(100) substrates, revealed that the Cu films are pure and exhibit good orientation. The growth rate of the films ranged from 0.025 to 0.035 Angstroms per laser pulse at the substrate temperature range between 50 and 600 degrees Celsius. Time-of-flight mass spectroscopy of the films revealed that the relative placement of the pulsed valve and copper target, and the relative timing of the gas and laser pulses determine film purity.

Cross-sectional scanning tunneling microscopy results on GaSb quantum wells and dots in GaAs are found to exhibit a narrow, sharply defined contrast of the nanostructure at negative sample bias, but a smoothly broadened contrast at positive sample bias. This contrast is related to the specific type-II band alignment of GaSb/GaAs heterostructures in combination with tip-induced band bending. The corresponding model is quantitatively verified by numerical simulations of band bending and tunnel current profiles combined with calculations of cleavage-induced strain relaxation. [ABSTRACT FROM AUTHOR]

Using plan-view and cross-sectional scanning tunneling microscopy, the shape and composition of InAs/GaAs quantum dots are investigated before and after capping by GaAs. During capping, the original pyramidally shaped quantum dots become truncated, resulting in a flat (001) top facet and steeper side facets. The InAs quantum dots are found to be intermixed at their top with GaAs due to material rearrangement. Since the bottom interface of quantum dots and wetting layer is always sharp, this intermixing occurs during capping and not during quantum dot growth. Considering strain energies, a model for the capping is presented. [ABSTRACT FROM AUTHOR]

Investigates the interaction and energy transfer of a laser ablation plasma of Ti with a pulsed N2 supersonic expansion using time-of-flight quadrupole mass spectroscopy and Langmuir probe techniques. Coupling of the nascent plasma with the gas pulse; Timing between the gas pulse and ablation plume; Ion signal quenching by the N2 number density.