| 摘要 |
PURPOSE:To reduce an electric current in the OFF state of a thin-film transistor and to reduce the irregularity in the device characteristic by a method wherein semiconductor layers for the thin-film transistor are composed of a solid solution of CdSe- CdTe. CONSTITUTION:Semiconductor layers at a thin-film transistor are composed mainly of a CdSe-CdTe solid solution, and are polycrystalline thin films containing Cu as an impurity. A semiconductor layer 4 on the side of a gate insulating film 3 is composed mainly of CdSe while a semiconductor layer 4' on the opposite side is composed mainly of CdTe. In addition, this thin-film transistor uses, as an evaporation source, the CdSe-CdTe solid solution or a substance where a small amount of Cu is added to a mixture of CdSe and CdTe, and uses a semiconductor layer formed after the evaporation source has been heated and evaporated. By using the solid solution of CdSe and CdTe or the mixture as the evaporation source and by making use of the difference in the vapor pressure between CdSe and CdTe, the semiconductor layer 4' containing more CdTe is formed on the rear of the semiconductor layer while the semiconductor layer 4 containing more CdSe is formed on the surface. The rear of the semiconductor layer for a TFT is made a P-type and a depletion layer is formed in this manner; as a result, an OFF electric current is reduced. |
