The effect of post-treatments on crystallization in a-Si:H/a-SiNx:H multilayers

Three post-treatments consisting of furnace annealing, rapid thermal annealing and laser annealing methods, were adopted to crystallize a-Si:H/a-SiNx:H multilayers with different-thickness a-Si:H sublayers. Raman and cross-sectioned TEM measurements show that the crystallization process of a-Si:H sublayers strongly depends on the thickness of the initial a-Si:H sublayer and the post-treatment process. When the thickness of a-Si:H sublayers is larger than 4.0 nm, the constrained a-Si:H sublayers are well crystallized by each of three methods. However, when the thickness of a-Si:H sublayers is smaller than 4.0 nm, the laser annealing method is the most advantageous to crystallize the samples compared to the other methods. For the rapid thermal process method, a higher crystallization temperature is needed for the thinner a-Si:H sublayers. In furnace annealing it is very difficult to achieve crystallization of the confined ultrathin a-Si:H sublayers. The mechanism of effects of the three post-treatments on the crystallization will be discussed.