A single phase of delafossite CuAlO2 (CAO) was successfully synthesized by a 600W microwave radiation
for 20 min. The CAO sample was composed of quite distorted single-crystalline plates with 200e350 nm
thick. Its atomic vibrations were detected at 760 and 550 cm1 belonging to AleO and CueO stretching,
respectively. The direct and indirect energy gaps were respectively determined to be 3.9 and 2.9 eV. The
photoluminescence (PL) at room temperature was at 585 nm (2.12 eV) corresponding to the indirect
energy gap and at 760 nm (1.63 eV) corresponding to the p-type native defect. For its thermoelectric (TE)
properties, the Seebeck coefficient (S) was positive value, with holes as the majority of charge carriers. By
increasing of the test temperature, both the electrical resistivity and absolute value of Seebeck coefficient
were decreased, but the power factor was in the opposite manner. The dimensionless figure of merit (ZT)
of the crystalline CAO was evaluated to be the maximum of 9 103 at 1073 K.