Rone,
- Assistant Professor, Department of engineering, Mangalmay Institute of Management &Technology, Greater Noida, Uttar Pradesh, India
Abstract
Engineering silicon secondary phases provides an effective route to tailor charge and thermal transport in Bi2Te3-based thermoelectric thin films. In this work, Bi 2 Te 3 :Si nanocomposite thin films with Si content of 0, 2.3, 4.5 and 8.2% were prepared by RF co- sputtering and the effect of Si addition on the structural, microstructural, electrical, thermoelectric and thermal transport properties was investigated. X-ray diffraction confirmed the retention of the polycrystalline rhombohedral Bi2Te3 structure, while changes in relative peak intensities suggested progressive modification and randomization of crystallite orientation. The orientation ratio was decreased from 3.01 for the pristine Bi2Te3 to 1.30, 1.00 and 0.96 for the 2.3, 4.5 and 8.2% Si films, respectively. Transmission electron microscopy showed that the distribution of the Si phase was mainly at the grain boundaries of Bi2Te3 with an amorphous nature, which demonstrates the formation of interfacial regions. Hall measurements revealed that Si incorporation had a significant effect on the carrier transport, with the mobility increasing from 200.6 to 380.4, while the carrier concentration decreased up to 4.5% Si and increased at 8.2% Si. The electrical transport at low temperature was consistent with a three-dimensional variable-range hopping mechanism in the range 100–250 K. The maximum absolute value of the Seebeck coefficient was obtained for 4.5% Si composition and was negative in the temperature range 315-480 K confirming n-type conduction. For this composition the maximum power factor was 2.75 at 315 K. Scanning thermal microscopy measurements showed a decrease of the thermal conductivity from 1.15 W m-1 K-1 for pristine Bi2Te3 to 0.57 W m-1 K-1 at 4.5% Si, proving an enhanced phonon scattering. Further Si addition increased thermal conductivity to 1.22 W m-1 K-1. Hence, the calculated dimensionless figure of merit increased from 0.42 to 1.45 for 4.5% Si and then decreased to 0.60 at 8.2% Si. These results indicate that controlled Si doping could balance the electronic transport and phonon scattering, which is a promising and practical grain-boundary engineering approach for enhanced thermoelectric performance for application.
Keywords: Silicon secondary phase; Grain-boundary engineering; Thermoelectric thin films; Charge transport; Phonon scattering; Electrical conductivity; Seebeck coefficient; Thermal conductivity; Thermoelectric figure of merit
[This article belongs to Journal of Thermal Engineering and Applications ]
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Journal of Thermal Engineering and Applications
| Volume | 13 | |
| Issue | 02 | |
| Received | 18/09/2026 | |
| Accepted | 19/09/2026 | |
| Published | 27/10/2026 | |
| Publication Time | 39 Days |