Statement of Research Interests
Dr.Ziad Yousef Abu Waar
Recently, there has been a great deal of interest in the fabrication of the low-
dimensional (nanostructures) semiconductors. Of particular interest are quantum dots and
ring like nanostructures. The motivations that simulate research in this field are basically
related to the possibility of using these materials for studying basic properties and
employing new devices. Here is a summery of some of my past research experiences in
this field.
I have designed a photoluminescence system to study the optical properties of the
fabricated nanostructure systems.
I have used droplet epitaxy technique to present a study on the formation of Ga
droplets on (100), (311)A and (511)A GaAs substrates in which both substrate
temperature and the amount of Ga supplied effects on the droplet formation, shape, size
and density for the three different surfaces have been investigated. It is important to
understand the Ga droplet formation, because it is the key point of understanding the
density, shape and size of the GaAs nanostructures.
Also I have used droplet epitaxy, by means of molecular beam epitaxy, on GaAs
(100) surfaces to study the evolution between GaAs/Al0.3Ga0.7As Single ring like and
double ring like nanostructures. Various growth temperatures, As4 fluxes, and monolayer
depositions are examined in order to observe how to change the ring structures. Also I
have investigated the influence of the size of GaAs/ Al 0.3 Ga 0.7 As double ring like
nanostructures on their optical properties.
I have performed a study of photoluminescence from uncapped non-oxidized and
oxidized InAs quantum dots on GaAs substrate as a function of the thickness of a GaAs
capping layer. A photoluminescence system in ultra-high-vacuum that was coupled onto
a molecular beam epitaxy chamber was used in order to avoid the oxidation of the
quantum dots surface.
We have presented a method to control lateral ordering of one and multilayered
In0.4Ga0.6As quantum dots grown on (100), (311)B, and (511)B GaAs substrates using
natural surface anisotropic for (100), surface steps on high index GaAs substrates and the
arsenic background.
I was able to fabricate self-organized InAs quantum rings using the Stranski-
Krastanov growth mode, and investigate their electronic and optical properties.
Although the big efforts spent in this field many low-dimensional systems and their
properties still rather ambiguous and unsettled. In my Future research I am planning to
use self-assembled growth methods, particularly Stranski-Krastanov and droplet epitaxy
to fabricate and characterize new and unexplored nonstructural systems using materials
from III-V compounds (GaAs, InAs, InGaAs, AlGaAs).