We report measurements of the structural, optical, transport, and magnetic properties of single crystals of the
anisotropic p-type transparent semiconductor CuAlO₂. The indirect and direct band gaps are 2.97 and 3.47 eV,
respectively. Temperature-dependent Hall measurements yield a positive Hall coefficient in the measured range
and an activated carrier temperature dependence. The resistivity is anisotropic, with the ab-plane resistivity
about 25 times smaller than the c-axis resistivity at room temperature. Both are activated with similar activation
energies. The room-temperature ab-plane mobility is relatively large at 3 cm² V⁻¹ s⁻¹, and we infer a
c-axis mobility of 0.12 cm² V⁻¹ s⁻¹. The Seebeck coefficient is positive at all measured temperatures, and has
a T⁻¹ dependence over most of the measured range. The low-temperature paramagnetic moment is consistent
with a spin-1/2 defect with a density of 3.4 X 10²⁰ cm⁻³. These results suggest that the conduction mechanism
for p-type carriers in CuAlO₂ is charge transport in the valence band and that the holes are thermally activated
from copper-vacancy acceptor states located about 700 meV above the valence-band maximum
