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An experimental method is defined that reduces the thermal conductivity in Si films by ~90 % compared to control samples, while keeping the thermoelectric power factor almost unchanged. This is done by creating vacancy-rich films via high-energy self-implantation of Si, followed by rapid-thermal annealing. TCAD simulations suggest that this approach is scalable for application in thin-film thermoelectric generators, as an alternative to more expensive and less Earth-abundant materials such as bismuth telluride. This approach to Si thermoelectrics could be straight-forward for scale-up to thin-film device dimensions, something that is a major challenge for other methods used for Si thermal conductivity reduction.

345 552 7158, www.researchgate.net/profile/nikolay_arutyunovThe vacancy-rich disordered regions (DR) playing a key role in improving the thermoelectric figure-of-merit of silicon thermoelectric generators by reducing (by $90%) the thermal conductivity, have been probed with positrons. The DR were created by irradiating n-Cz-Si(P) material with the fast reactor neutrons. The parameter of the electron density r s 0 % 2.18 a.u. contacting positrons in DR has been reconstructed using the data of the angular correlation of the annihilation radiation (ACAR); the amendments to the r s 0 value associated with the ion core electrons were taken into account. It is argued that the ion cores of atoms of silicon as well as the ones of the as-grown impurities (O, C) are involved in the open vacancy volume to be probed with positrons: a relaxation of the ion cores directed inward toward the vacancy volume seems to take place. These positron traps are formed beyond the vacancy-rich area of the disordered region. In the course of isochronal annealing, the traps are stable up to T anneal. % 520 8C when a recovery of ACAR parameters begins and then it continues up to $1050 8C.A vacancy center containing positrons in the open vacancy volume beyond the vacancy-rich area of the disordered region is shown schematically. The emission of electron-positron annihilation gamma-quanta dominates from within these positron traps. The values of both the electron-positron ion core radius (r m ) and electron density (parameter r s 0 ) suggest a relaxation directed toward inwards the open vacancy volume: the impurity atoms of oxygen and carbon are, perhaps, involved in the center.