Annealing in water vapor as a new method for improvement of silicon thin film properties

Microscopic study of the H2O vapor treatment of the silicon grain boundaries

“…shows the Hall mobility after treatment by different atmospheres (H 2 O vapor, D 2 O vapor, hydrogen and nitrogen) at 300°C as a function of treatment time, as reported by us at the last conference[1]. The remarkable improvement of the Hall mobility was repeatedly confirmed by the following experiments aimed at comparing the effect of H 2 O vapor and other atmospheres.Fig.…”

“…The Hall mobility was increased by the H 2 O vapor treatment although we did not observe any increase in the hydrogen concentration [1]. It is generally assumed that the defects might be passivated only by Si-H bonds formed by hydrogen diffusing from the plasma.…”

“…The results above show that the effect of H 2 O vapor treatment differs from a simple anneal in other atmospheres. It differs also from plasma hydrogenation -we have already reported that that the H 2 O vapor treatment creates no additional defects [1] observed after the prolonged hydrogenation [6].…”

“…In order to decrease the influence of grain boundaries it is necessary to passivate them, usually by plasma hydrogenation. We have recently proposed H 2 O vapor treatment as an alternative passivation method [1]. Treatment by H 2 O vapor offers advantages for solar cells industry, being a very simple, non-toxic process with a good uniformity even in large volumes.…”

“…Although improvement of the Si electronic properties by the H 2 O vapor treatment was already demonstrated [1,2], the underlying mechanism remains unclear. Electronic activity associated with the Si grain boundaries depends on the grain boundary character, defects and impurities, stress and other factors, complicating the search for H 2 O treatment mechanism.…”