Low resistivity p-type Zn1−xAlxO:Cu2O composite transparent conducting oxide thin film fabricated by sol–gel method

Highly transparent Cu2O-doped p-type Zn1−xAlxO (AZO; Al/Zn = 1.5 at%) conducting oxide films were synthesized on glass substrates using a cost effective low temperature sol–gel method. X-ray diffraction of the Cu2O-doped AZO (AZO:Cu2O) films revealed a polycrystalline Cu2O (1 1 0) peak. The I–V measurements of the p–n junction (ITO/AZO:Cu2O) revealed rectifying I–V characteristics, showing that these AZO:Cu2O films exhibit p-type conductivity. p-Type conductivity was achieved by annealing the AZO:Cu2O films in N2/H2 forming gas at 400 °C. The hole concentration, hole mobility and resistivity of the 0.5–2 mol% AZO:Cu2O films were 5.41 × 1018 to 1.99 × 1020 cm−3, 8.36–21.6 cm2/V s and 1.66 × 10−2 to 6.94 × 10−3 Ω cm, respectively. These results show that post-annealing in a forming gas is effective and practicable in producing p-type AZO.

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► Cu2O doped p-type AZO films was first prepared by sol–gel method.
► AZO:Cu2O films showed a polycrystalline Cu2O (1 1 0) and Cu (2 0 0) phases.
► p-Type conductivity was achieved by annealing in N2/H2 forming gas at 400 °C.
► p–n junction (ITO/AZO:Cu2O) revealed rectifying I–V characteristics.
► The mean optical transmittance of AZO:Cu2Ofilms was >90%.