| 摘要 |
PURPOSE:To vary the absorption characteristics according to the wavelength of signal light by flattening the bend of the energy band in a light absorption region by the carrier formed by incidence of the signal light. CONSTITUTION:A quantum well layer 25 of 100Angstrom and a quantum well layer 26 of 80Angstrom are laminated via a tunnel barrier layer 27 to constitute an asymmetric bond quantum well structure. The band structure is bent in the thermally equil. state because of the built-in electric field and is flattened because of screening by photoexcitation carriers when the intensity of the incident light is gradually increased. Since the carriers generated by the photoexcitation in such a manner negate the built-in electric field made in a p-i-n junction, the energy band is nearly flattened and the quantum levels are intersected at this time, by which the absorption peak wavelength is changed. The absorption characteristics are varied in this way according to the wavelength. |
