High mobility tin oxide deposition with methanol addition

SnO₂ coated glass is widely used in thin film PV. Atmospheric pressure chemical vapor deposition (APCVD) is the most common method of deposition and apart from a tin precursor and oxygen precursor, other additives can improve the layer quality. In this contribution, the beneficial effect of methanol is discussed. Undoped tin oxide (SnO₂) thin films have been deposited in a stagnant point flow chemical vapor deposition reactor. By adding methanol during the deposition process ten times more conductive SnO₂ films are obtained, with remarkably high mobility values of up to 55 cm²/Vs. The investigations on the morphological and structural properties indicate that the main effect of methanol is the densification of the SnO₂ films, which probably causes the improvement in the electrical properties. In all conditions the nucleation and coalescence phases take place very early in the growth. The films are already very conductive at a thickness below 10 nm, which is very beneficial to applications that have strict requirements in terms of film transparency.