| 摘要 |
<p>PURPOSE:To prevent an a-Si:H film of a device grade from being separated or floating thereby to improve the reliability of a device by laminating a buffer layer made of the a-Si:H film in which an optical band gap is specified between a substrate and the I-type layer. CONSTITUTION:A buffer layer 5 made of an a-Si:H film is interposed between a glass substrate 1 and an i-type layer 2 of a device grade. The layer 5 is formed of the nondoped a-Si:H film having 1.77eV or larger of the value of its optical band gap (Eg<opt>). The layer 5 is obtained by holding a substrate temperature 140-200 deg.C of low temperature at the time of forming a film by an RF glow discharging method. Since the layer 5 formed in this manner is so formed that an optical band gap is 1.77eV or larger, the influence of the internal stress is alleviated. Simultaneously, another role of the layer 5 is that the separation of the film due to a thermal stress scarcely occurs since the value of the thermal expansion coefficient is near that of a glass substrate 1 as compared with the layer 2.</p> |
