In-plane Cr2N−CrN metal-semiconductor heterostructure with improved thermoelectric properties

Enhanced Thermoelectric Properties by Embedding Fe Nanoparticles into CrN Films for Energy Harvesting Applications

“…The reference sample exhibited a Hall carrier concentration of ∼92 × 10 20 cm –3 and a Hall mobility of 0.3 cm 2 V –1 s –1 . Compared to values reported in the literature ((0.2–7) × 10 20 cm –3 ), the measured values of the carrier concentration are rather high while the Hall mobility falls within the reported values of 0.1–3 cm 2 V –1 s –1 . ,,, For both nanocomposites, the Hall carrier concentration dropped by 1 order of magnitude when the Fe-NPs were embedded into CrN and their electron drift mobilities were 1 order of magnitude higher than the reference sample. While these values differ from the monolithic sample, they fall in the ranges reported in the literature.…”

“…The low Seebeck coefficient values compared to other studies could be caused by the low thickness of the film and small CrN grains (<100 nm) which constitute the matrix. ,− In addition, the N-under-stoichiometric composition of the film could also influence the Seebeck coefficient of the reference sample where an under-stoichiometry reduces the Seebeck values . The reported room temperature electrical resistivity values exist in a wide range for CrN layers, ranging over 2.5 orders of magnitude from 1.7 × 10 –3 to 3.5 × 10 –1 Ω·cm. − Most studies suggest a strong correlation of the resistivity of the coatings and the crystal quality/morphology of the coating, where higher quality/larger grain reduce the electrical resistivity and increases the Seebeck coefficient. ,,, The CrN sample produced in this study was characterized by an electrical resistivity of 2.54 mΩ·cm, which falls within the lower range of resistivities mentioned above.…”

“…Transition metal nitride (ScN and CrN) systems have shown promise for use as thermoelectric materials . CrN-based materials, in particular, can exhibit both n-type or p-type semiconducting behavior, depending on doping and nitrogen stoichiometry. − The n-type CrN has a relatively high Seebeck coefficient (60–300 μV K –1 ), high electrical conductivity (0.6–3 mΩ·cm), and medium to low thermal conductivity (4–6 W m –1 K –1 ). ,, Due to the presence of magnetic disorder in CrN, lower thermal conductivities (∼2–3 W m –1 K –1 at room temperature (RT) , ) were reported compared to those of other transition metal nitrides with the same crystallographic structure (ScN, VN, TiN: 10–22 W m –1 K –1 at RT ,, ).…”

“…To avoid intermixing of the fillers and the matrix, phases that are immiscible or that interact poorly are often easier to synthesize. For example, nanoinclusions and nanoparticles have been reported to form during synthesis and were shown to improve the thermoelectric properties of the nanocomposites. ,,,, However, challenges remain in synthesizing (nano)­composites in which the matrix and (nano)­filler react with each other . To date, there are few reports on the design and synthesis of nanocomposite films containing nanosized fillers.…”

Recent progress of two-dimensional heterostructures for thermoelectric applications

“…Recently, Biswas et al proposed that inplane Cr 2 N-CrN metal-semiconductor heterostructures with appropriate Schottky barriers could achieve high thermoelectric performance due to the improved thermoelectric PF from the filtering effect of low-energy electrons. Moreover, further research found that the in-plane electronic conductivity was two orders of magnitude higher than that of CrN, and the Seebeck coefficient remained constant at approximately −150 µV K −1 , eventually reaching a PF of 2.1 mW mK −2 at 700 K [151]. This study provided theoretical guidance for the application of metal-semiconductor heterostructures in the field of thermoelectrics, indicating that this kind of material has broad prospects in the future.…”