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SSL Seminar Series 2001 No. 11
Title: The Evolution Behavior of (2?) reconstruction to (4x2)
on GaAs (001) surfaces
Speaker: Dr Xu Hai (SSL, NUS)
Date: 24 May 2001
Time: 5:00-6:00pm
Venue: Physics Resource Room S13, 02-16
Abstract
We have present the high–resolution scanning tunneling microscopy
(STM) images illustrating the evolution behavior of the transitional
(2?) reconstruction on GaAs(001) surfaces following a vacuum annealing
in the stages from 500-650 °C after routine cycles of sputtering cleaning.
At about 570 °C annealing temperature, a pair of Ga dimer rows between
the As chains with a periodicity of n=3 replaces the 2x periodicity
observed in normal (2?) symmetry. It was found that this transition
proceeds via the more As dimers missing from the surface exhibiting
the formation of non-perfect As “single?dimer chains along the [-110]
direction by high-resolution STM images. Following annealing at 570-600
°C range, small isolated regions of Ga- rich (4x2) reconstruction
are visible, which are surrounded by (nX6) regions. We have noted
significantly that this kind (4x2) reconstruction is consisting of
three-Ga dimer rows. A series of models have been proposed to interpret
this evolution process based on the high-resolution STM image. |
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