| 摘要 |
PROBLEM TO BE SOLVED: To achieve further improvement in efficiency, and to lower a threshold in a light-emitting element, especially in a laser device. SOLUTION: A plurality of quantum dots are formed on a first semiconductor layer having an energy-band gap larger than that of indium arsenide (InAs). Diameters of the quantum dots become smaller as they separate from the first semiconductor device, and the quantum dots are formed on the InAs. The plurality of quantum dots are covered with a first quantum dot trapping layer formed on the first semiconductor layer. The first quantum dot trapping layer is formed by an expression of In<SB>x</SB>Ga<SB>1-x</SB>As (0.1≤x≤0.17). A second quantum dot trapping layer is formed which is composed of a semiconductor having an energy-band gap larger than that of the first quantum dot trapping layer on the first quantum dot trapping layer. In the first quantum dot trapping layer, a microstructure is formed on the side of an interface of the first and second quantum dot trapping layer and above the quantum dots, wherein the microstructure controls the energy level of the quantum dots by its existence. COPYRIGHT: (C)2009,JPO&INPIT
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