https://doi.org/10.1140/epjb/e2005-00336-7
New EL2 structural model based on the observation of two sequential photoquenching processes
Núcleo de Física Aplicada, Instituto de Física,
Universidade de Brasília
CP 04455, CEP 70.919-970, Brasília, D.F., Brazil
Corresponding author: a priscila@fis.unb.br
Received:
17
March
2005
Published online:
28
October
2005
The EL2 photoquenching kinetics has been studied by measuring the transmittance of a 1.05 
m laser beam
as a function of time. The photoquenching curve presents two time constants that we associate to a two-stage transition
through an intermediate state to the final metastable state. This was verified by measuring the temperature dependence
of the transmittance with the sample prepared in a stage of partial photoquenching. Besides being also metastable, we
show that the intermediate state has an optical absorption-cross section that is temperature dependent. In order to
explain the existence of such a state, we propose a new structural model for the EL2 in which the motion of an arsenic
atom finds two metastable positions after photoexcitation. Our model is based on a mixture of features derived from the
models proposed by Chadi and Chang [1] and more recently by Fukuyama
et al. [2].
PACS: 61.72.Bb – Theories of crystal defects / 61.72.Ji – Point defects (vacancies, interstitials, color centers, etc.) and defect clusters / 78.30.Fs – III-V and II-VI semiconductors
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005
