Transparent conducting Ga-doped ZnO thin films grown by reactive co-sputtering of Zn and GaAs

• Ga-doped ZnO films have been deposited by reactive co-sputtering of Zn and GaAs.
• Transparent and conducting films are deposited at 375 °C and (3.5%) O2–Ar mixture.
• Films deposited with 1% GaAs coverage exhibit the lowest resistivity of 9 × 10− 6 Ω-m.
• The transparent conducting films exhibit plasma resonance and band gap widening.

Transparent conducting Ga-doped ZnO films have been deposited by rf reactive magnetron co-sputtering of Zn and GaAs in Ar–O2 mixture at a total flow rate of 30 sccm. Ga-doped ZnO films deposited with 1% GaAs target area coverage exhibit high transparency and low electrical resistivity in a narrow operational window of substrate temperature in the range of 350–400 °C and 3–4% O2 in the sputtering gas mixture. The film deposited under optimized conditions contains low arsenic impurity (~ 0.1 at.%) and exhibits ~ 80% or higher average transmittance in the visible region and electrical resistivity of ~ 9 × 10− 6 Ω-m, which corresponds to sheet resistance of 12–15 Ω/sq. The film exhibits carrier concentration ~ 7 × 1026 m− 3 and Hall mobility ~ 10− 3 m2 V− 1 s− 1. The high carrier concentration of the film results in the appearance of plasma resonance at ~ 1400 nm followed by high reflectance at longer wavelengths and widening of the band gap to ~ 3.7 eV due to heavy doping effects.