Toyoda Gosei Co., Ltd.

Other

Yuta Tezen

Masayoshi Koike

Toshio Hiramatsu

Seiji Nagai

Akira Kojima

Shiro Yamazaki

Shiro Yamasaki

Kazuyoshi Tomita

Hiroshi Yamashita

Tamiyo Umezaki

A first Group III nitride compound semiconductor layeris etched, to thereby form an island-like structure such as a dot-like, stripe-shaped, or grid-like structure, so as to provide a trench/post. Thus, a second Group III nitride compound layercan be epitaxially grown, vertically and laterally, from a top surface of the post and a sidewall/sidewalls of the trench serving as a nucleus for epitaxial growth, to thereby bury the trench and also grow the layer in the vertical direction. In this case, propagation of threading dislocations contained in the first Group III nitride compound semiconductor layercan be prevented in the upper portion of the second Group III nitride compound semiconductorthat is formed through lateral epitaxial growth. As a result, a region having less threading dislocations is formed at the buried trench.

Method for fabricating group III nitride compound semiconductors and group III nitride compound semiconductor devices

The present invention provides a Group III nitride compound semiconductor with suppressed generation of threading dislocations. A GaN layeris subjected to etching, so as to form an island-like structure having a shape of, for example, dot, stripe, or grid, thereby providing a trench/mesa structure, and a maskis formed at the bottom of the trench such that the upper surface of the maskis positioned below the top surface of the GaN layer. A GaN layeris lateral-epitaxially grown with the top surfaceof the mesa and sidewallsof the trench serving as nuclei, to thereby bury the trench, and then epitaxial growth is effected in the vertical direction. In the upper region of the GaN layerformed above the maskthrough lateral epitaxial growth, propagation of threading dislocations contained in the GaN layercan be prevented.

A sapphire substrateis etched so that each trench has a width of 10 &#x3bc;m and a depth of 10 &#x3bc;m were formed at 10 &#x3bc;m of intervals in a stripe pattern. Next, an AlN buffer layerhaving a thickness of approximately 40 nm is formed mainly on the upper surface and the bottom surface of the trenches of the substrateThen a GaN layeris formed through vertical and lateral epitaxial growth. At this time, lateral epitaxial growth of the buffer layerwhich was mainly formed on the upper surface of the trenches, filled the trenches and thus establishing a flat top surface. The portions of the GaN layerformed above the top surfaces of the mesas having a depth of 10 &#x3bc;m exhibited significant suppression of threading dislocation in contrast to the portions formed above the bottoms of the trenches.

Group III nitride compound semiconductor devices and method for fabricating the same

A first Group III nitride compound semiconductor layeris etched, to thereby form an island-like structure such as a dot-like, stripe-shaped, or grid-like structure, so as to provide a trench/mesa such that layer different from the first Group III nitride compound semiconductor layeris exposed at the bottom portion of the trench. Thus, a second Group III nitride compound layercan be epitaxially grown, laterally, with a top surface of the mesa and a sidewall/sidewalls of the trench serving as a nucleus, to thereby bury the trench and also grow the layer in the vertical direction. In this case, propagation of threading dislocations contained in the first Group III nitride compound semiconductor layercan be prevented in the upper portion of the second Group III nitride compound semiconductorthat is formed through lateral epitaxial growth. Etching may be performed until a cavity portion is provided in the substrate. The layer serving as a nucleus of ELO may be doped with indium (In) having an atomic radius greater than that of gallium (Ga) serving as a predominant element. The first semiconductor layer may be a multi-component layer containing a plurality of numbers of repetitions of a unit of a buffer layer and a single-crystal layer.

Production method of III nitride compound semiconductor and III nitride compound semiconductor element

When a substrate layer (desired semiconductor crystal) made of a group III nitride compound is grown on a base substrate comprising a lot of projection parts, a cavity in which a semiconductor crystal is not deposited may be formed between each projection part although it depends on conditions such as the size of each projection part, arranging interval between each projection part and crystal growth. So when the thickness of the substrate layer is sufficiently larger compared with the height of the projection part, inner stress or outer stress become easier to act intensively to the projection part. As a result, such stress especially functions as shearing stress toward the projection part. When the shearing stress becomes larger, the projection part is ruptured. So utilizing the shearing stress enables to separate the base substrate and the substrate layer easily. The larger the cavities are formed, the more stress tends to concentrate to the projection parts, to thereby enable to separate the base substrate and the substrate layer more securely.

Production method for semiconductor crystal and semiconductor luminous element

Method for producing group III nitride compound semiconductor and group III nitride compound semiconductor device

A sapphire substrateis etched so that each trench has a width of 10 &#x3bc;m and a depth of 10 &#x3bc;m were formed at 10 &#x3bc;m of intervals in a stripe pattern. Next, an AlN buffer layerhaving a thickness of approximately 40 nm is formed mainly on the upper surface and the bottom surface of the trenches of the substrate. Then a GaN layeris formed through vertical and lateral epitaxial growth. At this time, lateral epitaxial growth of the buffer layer, which was mainly formed on the upper surface of the trenches, filled the trenches and thus establishing a flat top surface. The portions of the GaN layerformed above the top surfaces of the mesas having a depth of 10 &#x3bc;m exhibited significant suppression of threading dislocation in contrast to the portions formed above the bottoms of the trenches.

Group III nitride compound semiconductor and method for manufacturing the same

The present invention provides a Group III nitride compound semiconductor with suppressed generation of threading dislocations. A GaN layeris subjected to etching, so as to form an island-like structure having a shape of, for example, dot, strip, or grid, thereby providing a trench/mesa structure, and a maskis formed at the bottom of the trench such that the upper surface of the maskis positioned below the top surface of the GaN layer. A GaN layeris lateral-epitaxially grown with the top surfaceof the mesa and sidewallsof the trench serving as nuclei, to thereby bury the trench, and then epitaxial growth is effected in the vertical direction. In the upper region of the GaN layerformed above the maskthrough lateral epitaxial growth, propagation of threading dislocations contained in the GaN layer iscan be prevented.

Methods for fabricating group III nitride compound semiconductors and group III nitride compound semiconductor devices

A GaN layeris subjected to etching, so as to form an island-like structure having, for example, a dot, stripe, or grid shape, thereby providing a trench/mesa structure including mesas and trenches whose bottoms sink into the surface of a substrate baseSubsequently, a GaN layeris lateral-epitaxially grown with the top surfaces of the mesas and sidewalls of the trenches serving as nuclei, to thereby fill upper portions of the trenches (depressions of the substrate base), and then epitaxial growth is effected in the vertical direction. In this case, propagation of threading dislocations contained in the GaN layercan be prevented in the upper portion of the GaN layerthat is formed through lateral epitaxial growth. Thereafter, the remaining GaN layeris removed through etching, together with the GaN layerformed atop the GaN layerand subsequently, a GaN layeris lateral-epitaxially grown with the top surfaces of mesas and sidewalls of trenches serving as nuclei, the mesas and trenches being formed of the remaining GaN layerthereby producing a GaN substratein which threading dislocations are considerably suppressed. When the area of a portion of the GaN layerat which the GaN substrateis in contact with the substrate baseis reduced, separation of the GaN substratefrom the substrate baseis readily attained.

Method for fabricating Group III nitride compound semiconductor substrates and semiconductor devices

By using a mask , a first Group III nitride compound semiconductor layer is etched, to thereby form an island-like structure such as a dot-like, striped-shaped, or grid-like structure, so as to provide a trench/post. Thus, without removing the mask formed on a top surface of the upper layer of the post, a second Group III nitride compound layer can be epitaxially grown, vertically and laterally, with a sidewall/sidewalls of the trench serving as a nucleus, to thereby bury the trench and also grow the layer in the vertical direction. The second Group III nitride compound layer does not grow epitaxially on the mask . In this case, propagation of threading dislocations contained in the first Group III nitride compound semiconductor layer can be prevented in the upper portion of the second Group III nitride compound semiconductor that is formed through lateral epitaxial growth and a region having less threading dislocations can be formed in the buried portion of the trench.

A semiconductor laser comprises a sapphire substrate , an AlN buffer layer , Si-doped GaN n-layer , Si-doped Al Ga N n-cladding layer , Si-doped GaN n-guide layer , an active layer having multiple quantum well (MQW) structure in which about 35 &angst; in thickness of GaN barrier layer and about 35 &angst; in thickness of Ga In N well layer are laminated alternately, Mg-doped GaN p-guide layer , Mg-doped Al Ga N p-cladding layer , and Mg-doped GaN p-contact layer are formed successively thereon. A ridged hole injection part B which contacts to a ridged resonator part A is formed to have the same width as the width w of an Ni electrode . Holes transmitted from the Ni electrode are injected to the active layer with high current density, and electric current threshold for laser oscillation can be decreased. Electric current threshold can be improved more effectively by forming also the p-guide layer to have the same width as the width w of the Ni electrode

Group III nitride compound semiconductor laser

A guide layer is formed to have a superlattice structure comprising five pairs of layers of AlGaN and InN, each having a thickness of about 10 nm. The guide layer has a total thickness of about 0.1 &mgr;m. The guide layer so structured has a reduced elastic constant such that the guide layer acts as a stress relieving layer.

Laser diode using group III nitride group compound semiconductor

A light emitting device using a group III nitride group compound semiconductor is disclosed. The device includes a substrate, a group III nitride group compound semiconductor layer, and a rectangular parallelepiped stack Rd which is formed by etching multiple group III nitride group compound semiconductor layers laminated on the group III nitride group compound semiconductor layer. The group III nitride group compound semiconductor layer comprises regions, which have many defects and less defects, respectively, and are formed in a striped pattern. Each of the boundaries between the regions with less defects and more defects or a plane which includes a longitudinal edge of the buffer layer is vertical to the substrate and parallel to a longitudinal plane of the rectangular parallelepiped stack Rd. The boundaries and two stack facets Mrr of the rectangular parallelepiped stack Rd are parallel to each other.

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Aichi, Japan

Yuta Tezen