Synthesis and characterization of NiO-doped p-type AZO films fabricated by sol-gel method

NiO-doped p-type AZO (Al/Zn = 1.5 at.%) films were synthesized on glass substrates using a simple and low cost sol-gel solution method. p-type conductivity could be achieved by annealing the NiO:AZO films in N ₂/H ₂ forming gas at 550 °C. The real Al/Zn and Ni/Zn ratio, hole concentration, hole mobility and resistivity of the 1.5-2 mol% NiO-doped AZO films were 0.26-0.29, 0.06-0.09, 3.15 × 10 ¹⁸-2.18 × 10 ²⁰ cm ^{- 3}, 2.33-12.76 cm ²/Vs, and 2.39 × 10 ^{- 1}-1.24 × 10 ^{- 2} ω cm, respectively. I-V measurements of the p-n junction (ITO/NiO:AZO) revealed rectifying I-V characteristics, confirming that these NiO:AZO films exhibit p-type conductivity. This study opens the possibility of developing highly conductive p-type composite transparent conducting oxides for optoelectronic devices. © 2011 Elsevier B.V. All rights reserved.