Recrystallization of amorphous silicon deposited on ultra thin microcrystalline siliconlayers

摘要

This study reports on a method to reduce the thermal crystallization time and temperature of amorphous silicon films by initially depositing an ultra thin um c-Si:H seed layer.After rapid thermal annealing (RTA), films were electron diffraction,atomic force microscopy,and dark and photocurrent.The results show that the microcrystalline particles in the seed layer act as nucleation centers, promoting crystallization of a-Si:H at lower temperatures and at shorter times,compared to a-Si:H films deposited without any seed layer.Additionally,it was found that the seed layer affects the orientation fothe crrystallized films.The dark current increases abruptly over 4 orders of magnitude in the first 15 second anneal,then decreases as the time increases,and tends to saturate.The photocurrent has an opposite behavior.These transport results can be understood in terms of a change in defect density and band gap shrinkage.