Abstract
This talk concerns with various aspects of ZnO-based thin films forphotovoltaic applications. In particular, emphasis has been given tounderstand dynamics of thin film growth by studying temporal and spatialevolution of surface roughness within framework of the dynamic scalingtheory. The films deposited at room temperature by RF magnetron sputteringfrom a ceramic target follow anomalous (super-rough) scaling behaviorcharacterized by global roughness and growth exponents clearly distinctfrom the local ones. The observed anomalous scaling and high growthexponents are correlated to the shadowing effect arising due tonon-uniform flux distribution favored by the 30-tilt of thesubstrates. The scaling exponents and hence the growth dynamics are foundto be strongly dependent on the process parameter, namely the RF powerduring sputtering. While the roughness exponent α is stable at1.5±0.2, the growth exponents βlocal and β decrease with thedecrease in the RF power. A dominant anisotropic growth of crystallites athigh powers is believed to be the main reason for the power-dependentroughening behavior. Besides, thickness-dependent film properties, role ofsputtering configuration and influence of the RF power on film properties,which assume much importance from technological point of view, have beendiscussed. It has been shown that thickness-dependent stress cancounteract the typical carrier concentration dependent broadening of bandgap observed in degenerate semiconductors. The process parameters (forexample, RF power) and sputtering configuration are shown to havetremendous impact on film properties. A very brief introduction to ourother research efforts (that includes research in flexibleoptoelectronics, alternate absorber layers for inorganic solar cells,etc.) is also presented.
24-08-2026