Sol–Gel Processed p-Type CuAlO2 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 CuAlxOy semiconductor thin films were fabricated by sol-gel method and integrated as channel layers in thin-film transistors (TFTs). The electrical performances of CuAlxOy TFTs, together with the characteristics of CuAlxOy 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 Ta 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.