Ziad Y Abuwaar

Publications (3)3.98 Total impact

• Source

  Available from: comp.uark.edu

  Article: Design of Nanostructure Complexes by Droplet Epitaxy

  Jihoon H. Lee, Zhiming M. Wang, Ziad Y. AbuWaar, Gregory J. Salamo
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  ABSTRACT: We demonstrate a number of unseen self-assembled nanostructure complexes fabricated on various GaAs surface indexes by droplet epitaxy. Even under identical growth conditions, the configuration of nanostructure complexes is distinctive on each surface. The morphology evolution of nanostructure complexes is kinetically and energetically analyzed in determining the correlation between shape of nanostructure complexes and atomic surface matrixes with atomic ball−stick models. By systematically varying growth environment, we report many uncanny nanostructure complexes on given surface indexes.
  01/2009;
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  Available from: uark.edu

  Article: Observation of Ga droplet formation on (311)A and (511)A GaAs surfaces.

  Ziad Y Abuwaar, Zhiming M Wang, Jihoon H Lee, Gregory J Salamo
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  ABSTRACT: Using (100) GaAs substrates as a reference, we present a study of the formation of Ga droplets on (311)A and (511)A GaAs substrates in which the effect of both the substrate temperature and the amount of Ga supplied on the droplet density and height for the three different surfaces have been investigated. Droplets on (100) substrates show a round shape; however, they appear as elongated balls with tails along the [Formula: see text] direction of the (311)A substrate and the [Formula: see text] direction of the (511)A substrate. It has been found that the Ga droplets on (511)A surfaces have lower densities and higher heights than those on (100) substrates. In contrast, Ga droplets on (311)A surfaces have lower heights and much higher densities compared to those for both (100) and (511)A. We observed that the decrease in the droplet density with increasing growth temperature for both (311)A and (511)A is more than twice that for the (100)GaAs surface due to the larger drop in the nucleation rate. Based on these observations, we offer a physical explanation based on the thermodynamics and the anisotropy of the high-index surfaces.
  Nanotechnology 08/2006; 17(16):4037-40. · 3.98 Impact Factor
• Source

  Available from: uark.edu

  Article: Optical behavior of GaAs∕ AlGaAs ringlike nanostructures

  Ziad Y Abuwaar, Yuriy I Mazur, Jihoon H Lee, Zhiming M Wang, Gregory J Salamo
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  ABSTRACT: Atomic force microscopy and photoluminescence PL measurements were carried out to investigate the role of the morphology of GaAs/ Al 0.3 Ga 0.7 As ringlike nanostructures on their optical properties. A small amount of Ga material less than three monolayers was used to fabricate single ringlike and double ringlike DRL nanostructures using droplet epitaxy technique. The height of the ringlike nanostructures increased with the increase of the Ga material while the corresponding PL emission energy was found to decrease as the ringlike nanostructure height increased. The PL peak energy showed a blueshift with increasing excitation intensity that can be understood as due to state filling while increasing temperature showed that the peak energy of the larger DRL nanostructures redshifts at a lower rate than the small ones due to larger confinement potential and lower energy emissions. © 2007 American Institute of Physics.