Investigation and control of microcracks in tin oxide gas sensing thin-films

In this paper, the role of microcracks in tin oxide gas sensing thin-films caused by high temperature annealing is discussed. In our research, cracks in rf sputtered tin oxide thin-films annealed at different conditions were investigated with scanning electron microscopy (SEM). Two techniques were used to reduce the cracking. The first was the use of tin oxide thin-films with copper-doping. The second method involved smoothing the underlying surface through the use of phosphorus-doped silicon glass (PSG). The role of the cracks for enhancing diffusion of moisture and oxygen is discussed using a revised short-circuiting pathway model.