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US 5,331,656 AGranted
Very short wavelength semiconductor laser
AssigneeHitachi, Ltd.
InventorToshiaki Tanaka
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AssigneeHitachi, Ltd.
InventorToshiaki Tanaka
Estimating the term…
A laser device, for example, a diode, is provided which has an oscillation wavelength shorter than 600 nm by using III-V semiconductor materials. This is achieved by using nitrogen doping with GaInP material on a GaP substrate to increase the critical layer thickness of the strained layer. As one example, the following layers can be epitaxially-grown in order on an n-type GaP substrate 1 by a molecular beam epitaxy (MBE) method: a Si-doped n-type Al.sub.y Ga.sub.l-y P optical waveguide layer; a multiple quantum well layer made by repeatedly forming four nitrogen-doped Ga.sub.x1 In.sub.1-x1 P quantum barrier layers and three nitrogen-doped Ga.sub.x2 In.sub.1-x2 P quantum well layers; a Zn-doped p-type Al.sub.y Ga.sub.1-y P optical waveguide layer; a Zn-doped p-type Ga.sub.x3 In.sub.1-x3 P thin layer; and a Zn-doped p-type Al.sub.y Ga.sub.1-y P optical waveguide layer. Next, the thin Ga.sub.x3 In.sub.1-x3 P layer is processed to form a ridge stripe. Then, an n-type Gap current constriction layer is selectively grown and a p-electrode and an n-electrode are formed. Using such a structure, it is possible to obtain a yellow laser element having a threshold current of 100 to 150 mA and an oscillation wavelength of 565 to 580 nm controlled in the transverse mode under continuous-wave (CW) room-temperature operation. Other embodiments use either a single quantum well layer or superlattice layers to obtain either yellow-green light or orange light of very short wavelengths.
A semiconductor laser diode comprising a double heterojunction structure formed on a GaP semiconductor substrate, wherein an optical waveguide layer and an active layer are grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE), wherein the optical waveguide layer has a large bandgap energy and is made of Al.sub.y Ga.sub.1-y P (0.ltoreq.y.ltoreq.1), wherein the active layer has a small bandgap energy and is made of Ga.sub.x In.sub.1-x P (0<x<1) of the direct transition type, wherein at least one of the optical waveguide layer and the active layer is doped with nitrogen as an impurity dopant in addition to a dopant of a conductivity type, and wherein the Ga.sub.x In.sub.1-x P active layer is formed on the semiconductor substrate to a thickness less than a critical thickness for a composition "x" (wherein the critical thickness is a maximum thickness of said active layer, above which dislocations will be formed in said active layer due to compressive strain).
A semiconductor laser diode comprising a double heterojunction structure formed on a GaP semiconductor substrate, including an Al.sub.y Ga.sub.1-y P (0.ltoreq.y.ltoreq.1) optical waveguide layer having a predetermined large bandgap energy, and a compressively strained Ga.sub.x In.sub.1-x P (0<x<1) active layer with a predetermined small bandgap energy of the direct transition type, wherein at least one of the optical waveguide layer and the active layer is doped with nitrogen as an impurity dopant in addition to a dopant of a conductivity type, and wherein the compressively strained Ga.sub.x In.sub.1-x P active layer is formed on the semiconductor substrate to a thickness less than a critical thickness for a composition "x" (wherein the critical thickness is a maximum thickness of said active layer, above which dislocations will be formed in said active layer due to compressive strain).
A semiconductor laser diode comprising a double heterojunction structure formed on a GaP semiconductor substrate, including an Al.sub.y Ga.sub.1-y P (0<y<1) optical waveguide layer having a predetermined large bandgap energy, and a compressively strained Ga.sub.x In.sub.1-x P (0<x<1) active layer with a small forbidden band width of the direct transition type, wherein the compressively strained Ga.sub.x In.sub.1-x P active layer is formed on the semiconductor substrate to a thickness less than a critical thickness for a composition "x" (wherein the critical thickness is a maximum thickness of said active layer, above which dislocations will be formed in said active layer due to compressive strain).
Dependencies are inferred from the claim text.