Rachel S. Goldman



2094 H.H. Dow Building

T: (734) 647-6821




Research Facilities


Synthesis of Low-Dimensional Semiconductor Structures: Directed Matrix-Seeding of Nanostructures

Collaborators: J.F. Mansfield
Sponsor: Radcliffe Fellowship, DCI Postdoctoral Fellowship HM1582-05-1-2027
Matrix-seeded growth is a promising approach for synthesis of luminescent semiconductor nanocomposites, consisting of nanocrystals in an amorphous matrix. In this approach, a supersaturated-layer is produced by high-energy ion-implantation, and annealing leads to nanocrystallization in the matrix. We recently synthesized GaN-rich nanocrystals within an amorphous matrix using N-ion implantation into epitaxial GaAs, followed by rapid-thermal annealing. Remarkably, these nanostructures exhibit significant near-infrared photoluminescence and cathodoluminescence, indicating sufficient crystallinity for electronic and optoelectronic devices, such as high-sensitivity photodetectors and high-power field-effect transistors. At the core of this program is a novel approach to semiconductor nanopatterning, based upon our recent observation of preferential nanocrystallization at regions of highest ion damage. In the directed matrix seeding process, we will use Ga+ or In+ FIB implantation into Ga(In)As films, in order to produce nanoscale regions of preferential damage, which will act as crystallization "seeds". We will then use a combination of blanket and FIB implantation of N and Mn to facilitate the nucleation of N- and Mn-rich nanostructures upon annealing.
Highlights (Click an image for more information)
  • Directed Matrix Seeding of Semiconductor Nanostructures

    GaAsN nanocrystals have been observed to preferentially form in GaAs in the areas of highest damage following N ion implantation and thermal annealing. This observation is being exploited as a mechanism for the ordering of such nanocrystals by damaging small regions of a sample using a Ga+ focused ion beam (FIB). The oval areas in the image represent damage caused by Ga ion implantation from the FIB, leading to preferential formation of GaAsN nanocrystals upon N ion implantation.