| 摘要 |
PURPOSE:To enable to stably perform the operation of an FET in a state of light irradiation and in a state of high electric field by a method wherein semiconductor layers of ultralow impurity density and n type semiconductor layers are alternately laminated on a semiconductor layer of ultraflow impurity density and as one side of the semiconductor layers become more distant from the semiconductor layer, the thickness of each of the one side of the semiconductor layers is gradually changed. CONSTITUTION:Semiconductor layers 8 are smaller than a semiconductor layer 2 in electron affinity and each of the semiconductor layers 8 has a thickness, through which an electron can be tunnelled, while semiconductor layers 9 are larger than the semiconductor layers 8 in electron affinity and each of the semiconductor layers 9 has a thickness of less than an electron wavelength. Here, the layers 8 have been formed in such a way that as the layers 8 become more distant from the layer 2, each of the layers 8 gradually becomes thinner, and the layer 2 has been formed of high-purity GaAs, the layers 8 have been formed of high-purity AlAs and the layers 9 have been formed of n type GaAs, for example. Electrons, which generate from the n type GaAs layers, spread in the high-purity AlAs layers as well by quantization level and distribute in the whole laminated structure of the n type GaAs layers and the AlAs layers, and a deep electron trapping level related to impurity is not formed. Therefore, even when a thermoelectron happens to jump into the laminated structure at the time of light irradiation, no fluctuation of the two-dimensional electron of two-dimensional electron gas 4 occurs. As a result, the operation of the FET is made stable. |
