Wayne State University, Department of Physics and Astronomy
Thursday 3 December 1998
Arsenic Dimer Dynamics
Caroline Morgan, Wayne State University
Semiconductor devices making use of low-dimensional structures put high
demands on the quality of growth. Very small structures, like quantum
dots, demand an understanding of growth processes on an atomic level.
Because of the current interest in smaller devices and low-dimensional
structures, a better understanding of the actual dynamic processes
occurring during growth is needed. Simple empirical models of growth
often contain unknown parameters, and can be too unspecific to lead to
the required level of understanding. In particular, since semiconductor
surfaces often have complicated reconstructions which require
high-quality methods of calculation, first-principles methods are needed
to investigate semiconductor growth processes. We have investigated
the interactions of the As2 molecule with GaAs surfaces using
first-principles (LDA and GGA) plane-wave pseudopotential calculations.
Results of these calculations will be used to show how the As molecules
are held at the surface until they can be funneled into strongly bound
sites during GaAs growth, and to explain the transition from the
β(that is meant to be a beta, but some browsers do not seem
be able to display it)2(2x4) to the c(4x4) surface reconstruction,
which occurs when
low-temperature growth is done under very arsenic-rich conditions.
Colloquium starts at 16:00 in Room 245 and lasts about 1 hour
including questions. Refreshements are served at 15:30 in room 245.