Sol-gel processed p-type CuAlO ₂ semiconductor thin films and the integration in transistors

Recently, p-type metal-oxide-semiconductors have attracted considerable interests for the applications in optoelectronic devices and low-power complementary metal-oxide-semiconductor circuits. In this report, ternary p-type CuAl _x O _y semiconductor thin films were fabricated by sol-gel method and integrated as channel layers in thin-film transistors (TFTs). The electrical performances of CuAl _x O _y TFTs, together with the characteristics of CuAl _x O _y thin films (e.g., crystalline phases, chemical compositions, surface morphology, and optical transmittances), were systematically studied at various annealing temperatures (T _a ). The phase-pure CuAlO ₂ thin films were obtained at T _a above 800 °C in N ₂ atmosphere. CuAlO ₂ TFTs annealed at 900 °C based on high-k Al ₂ O ₃ exhibited optimized electrical performance, including a hole mobility of 1.36 cm ² /Vs and ON/OFF current ratio of ∼1 × 10 ⁵ . This paper not only demonstrates the successful fabrication of high-quality p-type CuAlO ₂ semiconductor thin film and electronic devices by sol-gel process but also provides guidelines for related ternary p-type oxide semiconductor material and device performance improvements.