Patent ID: 6781157
Filing Date: 2004-08-24
Classification: B41J

Abstract:
A monolithic array-type light emitting device comprising a plurality of light emitting parts in one device, wherein:each of said light emitting parts comprises a light emitting diode having a laminate structure comprising an n-type GaAs substrate and, epitaxially grown on the n-type GaAs substrate in the following order, an n-type GaAs buffer layer, an n-type laminated reflection film formed of layer pairs each comprising AlGaAs layers different from each other in Al (aluminum) composition ratio, an n-type AlGaAs lower cladding layer, a p-type or undoped AlGaAs active layer, a p-type AlGaAs upper cladding layer, and a p-type GaAs contact layer; and each of said layer pairs constituting the laminated reflection film is a multilayered film of an AlX1Ga1âˆ’X1As layer and an AlX2Ga1âˆ’X2As layer where X1 and X2 satisfy 0X1Ga1âˆ’X1As layer and the AlX2Ga1âˆ’X2As layer, wherein the Al composition ratio is X1n2 where n1 represents the refractive index of the AlX1Ga1âˆ’X1As layer and n2 represents the refractive index of the AlX2Ga1âˆ’X2As layer, wherein the AlX1Ga1âˆ’X1As layer and the AlX2Ga1âˆ’X2As layer satisfy X1&gE;X and X2&gE;X where X1 and X2 are as defined above and X represents Al composition ratio in AlXGa1âˆ’Xas constituting the active layer, and wherein the AlX1Ga1âˆ’X1As layer satisfies EgX1&gE;E&lgr; wherein EgX1 represents the band gap energy of the AlX1Ga1âˆ’X1As layer and E&lgr; represents emission wavelength energy.