Nitride semiconductor laser device and method for fabrication thereof

Abstract

In a nitride semiconductor light-emitting device, and according to a method for fabricating it, a low-defect region having a defect density of 106 cm−2 or less and a carved region in the shape of a depressed portion are formed on the surface of a nitride semiconductor substrate, and the etching angle θ, which is the angle between the side surface portion of the depressed portion and an extension line of the bottom surface portion thereof as measured with the depressed portion seen in a sectional view, is in a range of 75°≦θ≦140°. This prevents the development of cracks, and reduces the creep-up growth from the bottom growth portion of the carved region, thereby reducing the film thickness of the side growth portion. This makes it possible to produce, with a high yield, a nitride semiconductor laser device having a nitride semiconductor growth layer with good surface flatness.

Description

[0001] This nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 2004-000328 filed in Japan on Jan. 5, 2004, the entire contents of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a nitride semiconductor laser device, and to a method for fabricating a nitride semiconductor laser device. More particularly, the present invention relates to a nitride semiconductor laser device that uses as the substrate thereof a nitride semiconductor. [0004] 2. Description of Related Art [0005] One feature of nitride semiconductors, for example GaN, AlGaN, GaInN, and AlGaInN, is that they have higher band gap energies than AlGaInAs-based and AlGaInP-based semiconductors. Another feature of such nitride semiconductors is that they are direct-transition semiconductor materials. [0006] Having these features, nitride semiconductors have recently been receiving much atte...

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Benefits of technology

[0043] The present invention has been devised to solve the conventionally encountered problems discussed above. It is, therefore, an object of the present invention to prevent cracks that develop in a nitride semiconductor growth layer when it is laid on top of a nitride semiconductor substrate to produce a nitride semiconductor laser device. It is another object of the present invention to provide a nitride semiconductor laser device wherein a nitride semiconductor growth layer is formed with good surface flatness as a result of a reduced film thickness in a side growth portion achieved by reducing creep-up growth from a bottom growth portion of a carved region. It is still another object of the present invention to provide a method for fabricating such a nitride semiconductor laser device.

[0045] In this structure, when the carved region in the shape of a depression is formed, by adjusting the etching angle of the sectional shape of the carved region within the range from 75° to 140°, it is possible to give it an inverted tapered shape. In this way, with the nitride semiconductor light-emitting device of the invention, it is possible to prevent the development of cracks in the nitride film semiconductor growth layer. Moreover, it is also possible to reduce the creep-up growth from the bottom growth portion of the carved region, and thereby to reduce the film thickness of the side growth portion.

[0048] With this structure, it is possible to prevent the development of cracks, and also to reduce the creep-up growth from the bottom growth portion of the carved region. Moreover, it is possible to reduce the film thickness of the side growth portion, and thus to form a nitride semiconductor growth layer with good surface flatness. As a result, it is possible to fabricate the nitride semiconductor laser device with a high yield.

Problems solved by technology

The reason is that, with an etching angle θ larger than 140°, it is difficult to fabricate the nitride semiconductor light-emitting device.

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