Yttrium Doped Copper (II) Oxide Hole Transport Material as Efficient Thin Film Transistor

This work reports development of yttrium doped copper oxide (Y-CuO) as a new hole transport material with supplemented optoelectronic character. The pure and Y-doped CuO thin films are developed through a solid-state method at 200 °C and recognized as high performance p-channel inorganic thin-film transistors (TFTs). CuO is formed by oxidative decomposition of copper acetylacetonate, yielding 100 nm thick and conductive (40.9 S cm^-1 ) compact films with a band gap of 2.47 eV and charge carrier density of ∼1.44×10¹⁹  cm^-3 . Yttrium doping generates denser films, Cu₂ Y₂ O₅ phase in the lattice, with a wide band gap of 2.63 eV. The electrical conductivity increases nine-fold on 2 % Y addition to CuO, and the carrier density increases to 2.97×10²¹  cm^-3 , the highest reported so far. The TFT devices perform remarkably with high field-effect mobility (μ_sat ) of 3.45 cm²  V^-1  s^-1 and 5.3 cm²  V^-1  s^-1 , and considerably high current-on/off ratios of 0.11×10⁴ and 9.21×10⁴ , for CuO and Y-CuO films, respectively (at -1 V operating voltage). A very small width hysteresis, 0.01 V for CuO and 1.92 V for 1 % Y-CuO, depict good bias stability. Both the devices work in enhancement mode with stable output characteristics for multiple forward sweeps (5 to -60 V) at -1V_g .