Pulsed DC bias effects on p-type semiconductor SrCu2O2 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 degrees 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 degrees 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 degrees C.