Laser synthesis of copper oxides 2D structures with high Seebeck coefficient and high thermoelectric figure of merit

Semiconductors are considered promising materials of thermo-converters and thermo-sensors. The photons generated by a KrF laser source (λ = 248 nm, τ FWHM ≤ 25 ns) were used for the synthesis of stable crystalline phases of copper oxides 2D single-layered semiconductor structures via the reaction of ablated copper atoms with oxygen molecules by reactive pulsed laser deposition (RPLD). Obtained semiconductor 2D single-layered structures of (23–75) nm thickness were deposited on 293, 600 or 800 K Si substrates in oxygen atmosphere at 1.0, 3.0 and 5.0 Pa. X-ray diffraction analysis evidenced polycrystalline structures of the deposits reviled of two crystalline semiconductor phases CuO (002) and CuO(111). Semiconductor temperature trend was detected with variable energy band gap ( E g ) in the range of (0.10–1.5) eV depending on substrate temperature, oxygen pressure and structure thickness. The optimum conditions were found out when the S coefficient was being homogeneously increased from 2.0 mV/K up to 10.5 mV/K and thermoelectric figure of merit ( ZT ) from 0.0035 up to 9.0 in the range of (290–340) K. The interpretation of behaviour for these 2D single-layered semiconductor structures of thermoelectric properties was provided. Obtained 2D single-layered structures based on copper oxides with such high S coefficient and high ZT are exceptionally strong candidates for a new effective thermo-sensors and thermo-converters operating at moderate temperature. Moreover, RPLD serves as an up to date method for the synthesis of 2D structures with such superior thermo-sensor and thermo-converter properties. These 2D single-layered structures based on copper oxides are among the most promising candidates based on non-toxic precursors for “green” technology fabrication of efficient thermo-sensors and thermo-converters.