  The increasing demand for renewable energy and shortage of resources in
today's world has been stimulating researchers to explore means for the
extraction of energy from wasted heat sources. Thermoelectric materials can
convert thermal energy directly into electric energy and vice versa. In this
paper, a phonon crystal structure has been proposed and characterized to study
its bandgap magnitude and the effect on the thermal conductivity which could
increase the efficiency of the thermoelectric materials. The novelty of this
paper is the phonon crystal structure that has been proposed and the method to
study the effects of different dimensional parameters of the phonon crystal
structure on the bandgap magnitude.
  The phonon crystal bandgap is simulated by the COMSOL software and then
validated with other literature results. Based on the validated simulation
model, a regression parameter model is developed from the COMSOL software
simulation.
  The model is used to predict the magnitude of the bandgap of the phonon
crystal structure from input design parameters where the sensitivity of the
design parameters and their interactions can be analysed. The design parameters
can be optimized for the biggest bandgap magnitude based on the regression
parameter model. The optimization results show a significant improvement in the
magnitude of the bandgap.
