Pulsed DC bias effects on p-type semiconductor SrCu₂O ₂ film deposited by RF magnetron sputtering

Transparent p-type semiconducting SrCu₂O₂ films have been deposited by RF magnetron sputtering under unbalanced bipolar pulsed DC bias on low-alkali glass substrates in a mixed gas of 1% H₂/Ar below 400 °C. The pulsed DC bias voltages to substrate were varied from 0 V to -200 V with a frequency of 350 kHz. The effect of pulsed DC bias on the structure and electrical and optical properties of SrCu₂O₂ films has been investigated using SEM, XRD, surface profiler, Hall measurements and UV-VIS spectrometer. The deposition rates of SrCu₂O₂ films under DC-pulsed bias show a maximum at -100 V bias, and decreased with increasing the bias voltage. XRD results of the as-deposited films under the bias voltage at 400 °C reveal SrCu₂O₂ polycrystalline phase, and increased crystallite size with increasing pulsed DC bias voltage. The SrCu₂O₂ films deposited under the pulsed-bias of -100 V exhibits the highest conductivity of 0.08 S/cm, and over 70% of transmittance at 550 nm. It is confirmed that the application of pulsed DC bias in sputtering improves the crystallization, crystal growth, and the electrical and optical properties eventually under 400 °C.