Semiconductor light emitting element and method for fabricating the same

The present patent application is a continuation of U.S. patent application Ser. No. 11/759,326, filed on Jun. 7, 2007, which is a continuation of U.S. patent application Ser. No. 10/891,968, filed on Jul. 15, 2004 (now U.S. Pat. No. 7,368,766), which is a divisional of U.S. patent application Ser. No. 10/011,552, filed on Nov. 6, 2001 (now U.S. Pat. No. 6,861,672), which is a divisional of U.S. patent application Ser. No. 09/080,121, filed on May 15, 1998 (now U.S. Pat. No. 6,326,638), which is a divisional of U.S. patent application Ser. No. 08/588,863, filed on Jan. 19, 1996 (now U.S. Pat. No. 5,787,104), the contents of which are incorporated by reference.

1. Field of the Invention

The present invention relates to a short-wavelength semiconductor light emitting element used in the fields of optical communications, optical information processing, and the like, and a method for fabricating the same.

2. Description of the Related Art

In recent years, with increased demands for short-wavelength semiconductor light emitting elements in various fields, studies focusing mainly in ZnSe and GaN as the materials for such elements have been vigorously conducted. As for ZnSe material, a short-wavelength semiconductor laser with an oscillation wavelength of about 500 nm has succeeded in oscillating consecutively at room temperature. Now, study and development for practical use of this material is under way. As for GaN material, a blue light emitting diode with high luminance has recently been realized. The reliability of this material as the light emitting diode is by no means inferior to that of other materials for semiconductor light emitting elements. GaN material is therefore expected to be applicable to a semiconductor laser. However, the properties of GaN material are not clearly known; moreover, GaN material has a hexagonal-system crystalline structure. Therefore, it is uncertain whether GaN material can provide characteristics durable enough for practical use when it is used as an element having a structure similar to that used for conventional cubic-system materials.

The semiconductor laser of this invention includes an active layer formed in a c-axis direction, wherein the active layer is made of a hexagonal-system compound semiconductor and anisotropic strain is generated in a c plane of the active layer.

In another aspect of the present invention, a method for fabricating a semiconductor laser is provided. The method includes the step of forming an active layer made of a hexagonal-system compound semiconductor in a c-axis direction, wherein the active layer is formed so that anisotropic strain is generated in a c plane.

Alternatively, the semiconductor light emitting element of this example includes: a semiconductor substrate; a stripe groove formed on a principal plane of the semiconductor substrate; and a semiconductor light emitting layer formed on the other principal plane of the semiconductor substrate.

Alternatively, the method for fabricating a semiconductor light emitting, element of this example includes the steps of: forming a stripe-shaped groove on a principal plane of a semiconductor substrate; and forming a light emitting element structure on the other principal plane of the semiconductor substrate.

Alternatively, the method for fabricating a semiconductor light emitting element of this invention includes the steps of: forming a stripe-shaped mask on a principal plane of a semiconductor substrate; etching the semiconductor substrate selectively using the mask; depositing material having a thermal expansion coefficient different from that of the semiconductor substrate on the semiconductor substrate selectively using the mask; and forming a light emitting element structure on the other principal plane of the semiconductor substrate.

Alternatively, the semiconductor light emitting element of this example includes: a semiconductor substrate; a stripe-shaped member formed on a principal plane of the semiconductor substrate, the member being made of a material having a thermal expansion coefficient different from that of the semiconductor substrate; and a semiconductor light emitting layer formed on the other principal plane of the semiconductor substrate.

Alternatively, the method for fabricating a semiconductor light emitting element of this example includes the steps of: forming a stripe-shaped member on a principal plane of a semiconductor substrate, the member being made of a material having a thermal expansion coefficient different from that of the semiconductor substrate; and forming a light emitting element structure on the other principal plane of the semiconductor substrate.

Alternatively, the method for fabricating a semiconductor light emitting element of this example includes the steps of: forming a light emitting element structure on a surface of a semiconductor substrate; and forming a stripe-shaped member on the other surface of the semiconductor substrate at 300° C. or more, the member being made of a material having a thermal expansion coefficient different from that of the semiconductor substrate.

Alternatively, the method for fabricating a semiconductor light emitting element of this example includes the steps of: forming a light emitting element structure on a principal plane of a semiconductor substrate; forming a stripe-shaped member on the other surface of the semiconductor substrate, the member being made of a material having a thermal expansion coefficient different from that of the semiconductor substrate; and heat-treating the semiconductor substrate at 500° C. or more.

Alternatively, the semiconductor light emitting element of this example includes: a semiconductor substrate; a first metal formed on a principal plane of the semiconductor substrate; a stripe-shaped second metal formed on the first metal; and a light emitting element structure formed on the semiconductor substrate.

Alternatively, the method for fabricating the semiconductor light emitting element of this example includes the steps of: forming a light emitting element structure on a principal plane of a semiconductor substrate; depositing a first metal on the other principal plane of the semiconductor substrate; and depositing a stripe-shaped second metal on the first metal.

Alternatively, the method for fabricating a semiconductor light emitting element of this invention includes the steps of: attaching a semiconductor substrate to a surface of a body which is part of a curved surface of a cylinder; and forming a light emitting element structure on the semiconductor substrate.

Alternatively, the semiconductor light emitting element of this invention includes: a substrate having a principal plane; and a wurtzite-type AlGaInN compound semiconductor formed on the substrate, wherein the substrate is made of a material of which thermal expansion coefficient is anisotropic in the principal plane.

Alternatively, the semiconductor light emitting element of this invention includes a substrate having a principal plane and a wurtzite-type AlGaInN compound semiconductor formed on the substrate, wherein the substrate is made of a material of which thermal expansion coefficient is greater in a first direction in the principal plane and smaller in a second direction vertical to the first direction than the thermal expansion coefficient of the wurtzite-type AlGaInN compound semiconductor.