Merits and Demerits of Transparent Conducting Magnetron Sputtered ZnO:Al, ITO and SnO2:F Thin Films for Solar Cell Applications

Transparent conducting ZnO:Al and indium tin oxide (ITO) thin films were deposited by magnetron sputtering under reactive environment. Both the transparent conducting oxide (TCO) films were exposed intentionally in hydrogen environment at 350 °C calcinations temperature to study the post treated TCO film’s opto-electronic, structural as well as surface morphological properties. Electrical resistivity of both ZnO:Al, ITO and SnO 2 :F films are comparable (order of 10 −4 Ω-cm), lowest sheet resistance are 8.5, 3.7 and 4.6 Ω/sq respectively and slightly improved after hydrogen exposure at 350 °C. Optical transmittance and internal texture of hydrogen environment exposed ZnO films remains invariant, but in case of ITO, SnO 2 :F films optical transmittance deteriorated drastically. Hexagonal wurtzite structure with (002) c-axis orientation is observed for pre- and post-hydrogen exposed ZnO films whereas internal texture as well as crystallographic orientation of ITO and SnO 2 :F films have significantly changed. Surface grains of ITO films have been significantly enhanced, but no such variations are observed in ZnO surface morphology. ZnO:Al and ITO films show unique plasmonic properties in near infrared transmittance due to free carrier generation in conduction band. Based on surface features/morphology, haze factor and internal texture light scattering mechanism is modeled.