| 摘要 |
PURPOSE:To reduce the ageing change of a drain current and to increase a mutual conductance of a thin film transistor (TFT) by varying the composition ratio of the material of a gate insulator layer in a thicknesswise direction. CONSTITUTION:A gate electrode 2 made of aluminum is formed on a glass substrate 1, and an insulator layer 7 which varies continuously in the composition ratio of materials to gradually increase a dielectric constant toward the surface of the film is formed on the electrode 2. When the layer 7 is formed of a composite insulating film made of two types or more of materials, it is generally known that the dielectric constant is varied when the composition ratio of the materials alter. Accordingly, the dielectric constant of the layer 7 in the surface contacted with a semiconductor layer 8 can be much reduced. Thus, the number of electrons attracted into the layer 7 can be reduced to decrease the variation in the drain current. |
