IMPROVED HYDROGEN DEPTH PROFILES WITH IN-CHAMBER ANNEALING OF HYDROGENATED AMORPHOUS-SILICON THIN-FILMS

We have undertaken a study on the influence of deposition temperature and an in-chamber annealing treatment on the hydrogen depth profiles o f sputter-deposited hydrogenated amorphous silicon (a-Si:H) thin films . Our results show that for higher temperature deposition (285-300 deg rees C), which leads to a lower degree of hydrogen incorporation, very steep hydrogen distribution profiles resulted. The hydrogen content a t the film-substrate interface of such films can be similar to 2/3 of that at the film's surface. It is believed that a strong hydrogen outd iffusion from the bulk took place during film growth at those relative ly high temperatures. When an in situ in-chamber annealing treatment w as carried out just after deposition and before samples reached room t emperature, hydrogen distribution through the film thickness showed a more homogeneous profile. Moreover, the resultant films appeared to be more dense when samples were subjected to this treatment in an atomic hydrogen atmosphere. (C) 1996 American Institute of Physics.