Structure change of a-C:H prepared by ionization deposition

A-C:H films were annealed in an attempt to investigate the stability of a-C:H films at high temperature. A T.T.T. (Time-Temperature-Transformation) diagram could be drawn up using the results of annealed a-C:H films under hydrogen ambient. According to the T.T.T. diagram, the annealed a-C:H films could be classified into three regions; an amorphous phase region, a reconstruction region and a crystallizing region. In the amorphous region (<873-1073 K), the effusion of hydrogen from the a-C:H films was observed but the structure change of the a-C:H films was not observed even though the annealing time was up to 1 Ms. The structure change of the a-C:H films occurred in the reconstruction region (873 K-1123 K). However, the crystal grains were not observed in this region. In the crystallizing region (> 1073-1173 K), the crystal grains which have a graphitic structure were formed in the matrix.