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 of sputter-deposited hydrogenated amorphous silicon (a-Si:H) thin films. Our results show that for higher temperature deposition (285-300 degrees C), which leads to a lower degree of hydrogen incorporation, very steep hydrogen distribution profiles resulted. The hydrogen content at 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 outdiffusion from the bulk took place during film growth at those relatively high temperatures. When an in situ in-chamber annealing treatment was carried out just after deposition and before samples reached room temperature, 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.