Structural and Opto-electronic characterization of CuO thin films prepared by DC reactive magnetron sputtering

Abstract

P-type CuO thin films have been deposited and optimized for large-area photodetection applications by tuning the sputtering pressure and oxygen to argon gas ratio, considering both high-temperature sputtering and post-annealing. The obtained layers show tunable bandgaps from 1.30 to 2.04 eV and Urbach energies lower than 8 meV. Reliable Hall measurements reveal the inverse double logarithmic relationship between Hall mobility and carrier concentration. By setting the optimal sputtering pressure of 10 mTorr (O2/Ar = 8/22 sccm) at the edge of oxidization and transition regimes, CuO with 1.64 eV bandgap reaches stable hole mobility of 34.2 cm2V−1 s−1 and hole concentration of 3.92 × 1014 cm−3 after 250 °C post-annealing. Considering heating at 150 °C during the deposition, CuO with 1.63 eV bandgap also reaches stable record hole mobility of 113.7 cm2V−1 s−1 and hole concentration of 1.39 × 1014 cm−3.