Thermoelectric and Transport Properties of Delafossite CuCrO2:Mg Thin Films Prepared by RF Magnetron Sputtering

Abstract

P-type Mg doped CuCrO2 thin films have been deposited on fused silica substrates by Radio-Frequency (RF) magnetron sputtering. The as-deposited CuCrO2:Mg thin films have been annealed at different temperatures (from 450 to 650 °C) under primary vacuum to obtain the delafossite phase. The annealed samples exhibit 3R delafossite structure. Electrical conductivity σ and Seebeck coefficient S of all annealed films have been measured from 40 to 220 °C. The optimized properties have been obtained for CuCrO2:Mg thin film annealed at 550 °C. At a measurement temperature of 40 °C, this sample exhibited the highest electrical conductivity of 0.60 S·cm−1 with a Seebeck coefficient of +329 µV·K−1. The calculated power factor (PF = σS²) was 6 µW·m−1·K−2 at 40 °C and due to the constant Seebeck coefficient and the increasing electrical conductivity with measurement temperature, it reached 38 µW·m−1·K−2 at 220 °C. Moreover, according to measurement of the Seebeck coefficient and electrical conductivity in temperature, we confirmed that CuCrO2:Mg exhibits hopping conduction and degenerates semiconductor behavior. Carrier concentration, Fermi level, and hole effective mass have been discussed.

Tuning the electrical properties of the p-type transparent conducting oxide Cu1−xCr1+xO2 by controlled annealing

“…This level of conductivities is usually reported for off-stoichiometric delafossites thin- films fabricated using non-equilibrium chemical methods as dynamic liquid injection chemical vapour deposition 10,11,14 or chemical spray deposition 12,13 . These values are significantly higher than those reported for intrinsic 20,21 or some doped 22,23 CuCrO 2 delafossites thin-films.…”

Assessment of thermodynamic data for CuCrO2 delafossite from calorimetric measurements

“…Among them, the cuprous chromite CuCrO 2 , also named "Mac Connellite" in its mineral form and sometimes noted as Cu 2 Cr 2 O 4 in older works, is one of the most promising candidates for transparent ptype conducting oxide in optoelectronic devices [1][2][3]. This compound is also of interest for its catalyst/photocatalytic [4,5] and thermoelectric applications [6][7][8]. Moreover, the CuCrO 2 phase presents remarkable physical properties such as multiferroic behavior [9,10] at low temperatures.…”

Copper Delafossites under High Pressure—A Brief Review of XRD and Raman Spectroscopic Studies

“…The electrochemical performance of nano CuAlO 2 with an average particle size of ≈20 nm demonstrated 12 times more catalytic activity in the electrolysis of water to the hydrogen evolution reactions and oxygen evolution reactions compared to bulk CuAlO 2 [28]. Research on thin films of delafossite is another interesting and widely investigated area for their potential uses in optoelectronic device fabrication [29][30][31][32]. As has been well established by the high pressure scientific community, compression is yet another way to engineer the crystal/electronic structure of materials, producing compounds with entirely different set of physical properties without altering their chemical composition [33,34].…”