OPTIMAL BAND GAP FOR IMPROVED THERMOELECTRIC PERFORMANCE OF TWO-DIMENSIONAL DIRAC MATERIALS
Thermoelectric properties of two-dimensional (2D) Dirac materials are calculated within linearized Boltzmann transport theory and relaxation time approximation. We find that the gapless 2D Dirac material exhibits poorer thermoelectric performance than the gapped one. This fact arises due to cance...
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| Format: | Theses |
| Language: | Indonesia |
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| Online Access: | https://digilib.itb.ac.id/gdl/view/42265 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Thermoelectric properties of two-dimensional (2D) Dirac materials are calculated
within linearized Boltzmann transport theory and relaxation time approximation.
We find that the gapless 2D Dirac material exhibits poorer thermoelectric performance
than the gapped one. This fact arises due to cancelation effect from electronhole
contributions to the transport quantities. Opening the band gap lifts this cancellation
effect. Furthermore, there exists an optimal band gap for maximizing figure
of merit (ZT) in the gapped 2D Dirac material. The optimal band gap ranges
from 6kBT to 18kBT, where kB is the Boltzmann constant and T is the operating
temperature in kelvin. This result indicates the importance of having narrow gaps
to achieve the best thermoelectrics in 2D systems. Larger maximum ZTs can also
be obtained by suppressing the lattice thermal conductivity. In the most ideal case
where the lattice thermal conductivity is very small, the maximum ZT in the gapped
2D Dirac material can be many times ZT of commercial thermoelectric materials. |
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