Synthesis process and thermoelectric properties of n-type tin selenide thin films

Abstract

Tin selenide (SnSe) is a very promising thermoelectric material, but there are few reports related to the thermoelectric properties of its thin films, especially for n-type SnSe. In this work, n-type SnSe thin films were synthesized via thermal evaporation using powdered SnSe that was prepared directly by mechanical alloying. It was found that the crystallinity of the films gradually improved and the closer the elemental ratio of Sn and Se was to a ratio of 1:1 with increasing the current through the tungsten boat during the thermal evaporation of the SnSe precursor from 100 to 130 A. Further, the thin films obtained at 120 A show the highest power factor (0.13 µW/mK 2) of all the samples fabricated in this study. The samples were then annealed, and the thermoelectric properties of the films were enhanced as this step improved their crystallinities. A Seebeck coefficient of over 100 µV/K could be achieved with an annealing time of 4 h. Combined with a recorded electrical conductivity of 47 S/cm, a maximum power factor of 120 µW/mK 2 at 473 K has been obtained for the annealed film with n-type conductive characteristics; this is nearly six times higher than that reported for polycrystalline n-type bulk SnSe at the same temperature.

Defect Engineering in Ultrathin SnSe Nanosheets for High-Performance Optoelectronic Applications

“…The SnSe prepared by the reaction of Sn and Se at high temperatures is a natural p-type semiconductor due to Sn vacancies . On the other hand, there are many studies that show SnSe to be an n-type semiconductor without any doping. − We found that these SnSe samples are all prepared by a high-temperature treatment using a SnSe source. Recently, Sraitrova et al observed that the concentration of Se vacancies in SnSe gradually increases with the increase in annealing temperature.…”

Advanced Thermoelectric Design: From Materials and Structures to Devices

“…Table summarizes the design routes and experimentally evaluated performance of state-of-the-art solid and flexible thermoelectric films (refs , , , , , , , , , , , − , , , , and − …”

The ultra-high thermoelectric power factor in facile and scalable single-step thermal evaporation fabricated composite SnSe/Bi thin films

“…Similar behavior was also observed by Wang et al in the SnSe film deposited via the TE technique and the n-type behavior of SnSe was observed due to a decreased atomic concentration of Se. 72 The induction of the Se vacancies leaves more electrons in the free state, resulting in the n-type conduction of SnSe, effectively increasing the carrier concentration in SnSe. The doping of the Bi in bulk and SnSe film has also been reported in the literature.…”

“…77,79,85 Also, SnSe with the vacancy of Se atoms shows such a type of behavior. 72 Furthermore, a detailed comparison of the thermoelectric performance (power factor) of SnSe is shown in ESI, † Table S1 and depicted in Fig. 5 indicates the nature of the material (whether it is a film, bulk, composite, etc.…”