Improvement of electrical and optical properties of molybdenum doped zinc oxide films by introducing hydrogen

Doped ZnO films are promising candidates as a front electrode in silicon film solar cells. In present work, we report on efforts to obtain highly conductive and transparent hydrogen and molybdenum co-doped ZnO (HMZO) films prepared by pulsed direct current (DC) magnetron sputtering. Investigations were made to see the effect of hydrogen (H2) flow rate on structural, electrical and optical properties. The results indicate that H2 flow rate has a considerable influence on the transparent conductive properties of molybdenum doped ZnO (MZO) films. A reduced resistivity of 69.2% and a broadening optical band gap of 5.7% were obtained with the optimal H2 flow rate of 5 sccm. The average transmittance of more than 86% in the range of 400–1100 nm was obtained with the optimal H2 flow rate. Crater-like surface morphology with root-mean-square (RMS) roughness of 46.5 nm was also obtained after etching by diluted hydrochloric acid (HCl). Such a co-doping growing method present here may be useful for wide spectra absorption thin film solar cells.