What is it about?
High quality and accurate computational data were obtained through first principle quantum mechanical calculations originated from Density functional theory with out the inclusion of empirical data (ab initio). The support of the computing facility allows us to carry out our research involving large scale atomistic simulations. The data we recently obtained clearly shows piezoelectricity in GaAs and InAs are proved to be nonlinear in relation to a general strain.
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Why is it important?
The high order fitting equation obtained through the parameterizations allowed us to directly evaluate higher order piezoelectric coefficients. By comparing with other and nonlinear models and also experimental data, we reached the conclusion that the validity of our model is correct in the limitation of small shear strain, particularly in case of (111) grown semiconductors. Such limitation however is not restricted under pseudomorphic growth in (001) direction where typically shear strain is small.
Perspectives
It is the kind of work that is likely to get cited as a seminal work. In terms of using the coefficients, the model is also easy enough to implement even for non specialists.
Dr Max A Migliorato
University of Manchester
We further validate our model through elasticity theory to demonstrate the sign of the polarization is found to be opposite to bulk values for an InAs semiconductor layer grown in the (001) direction of growth and is subject to 6-7% of lattice mismatch. This is additionally supported with experimental evidence (optical absorption spectra). Furthermore, our model provides a direct way in evaluating the polarization for any crystal structure described on the atomic level. This is mainly beneficial to researchers who use molecular dynamics and empirical methods for predicting bandstructure. The fundamental performance for semiconductor devices can be improved using small polarization created from strain and is likely to bring advantages in future photovoltaics devices.
Dr Geoffrey Tse
Southern University of Science and Technology
Read the Original
This page is a summary of: Non-linear piezoelectricity in zinc blende GaAs and InAs semiconductors, Journal of Applied Physics, August 2013, American Institute of Physics,
DOI: 10.1063/1.4818798.
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