Energy band engineering and controlled p-type conductivity of CuAlO 2 thin films by nonisovalent Cu-O alloying

The electronic band structure and p-type conductivity of CuAlO 2 films were modified via synergistic effects of energy band offset and partial substitution of less-dispersive Cu + 3d 10 with Cu 2+ 3d 9 orbitals in the valence band maximum by alloying nonisovalent Cu-O with CuAlO 2 host. The Cu-O/CuAlO 2 alloying films show excellent electronic properties with tunable wide direct bandgaps (∼3.46-3.87eV); Hall measurements verify the highest hole mobilities (∼11.3-39.5 cm 2 /Vs) achieved thus far for CuAlO 2 thin films and crystals. Top-gate thin film transistors constructed on p-CuAlO 2 films were presented, and the devices showed pronounced performance with I on / I off of ∼8.0×10 2 and field effect mobility of 0.97 cm 2 /Vs.