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.

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