Fujitsu Corporation

Other

Sharp Kabushiki Kaisha Corporation

Hajime Shoji

Hirohiko Kobayashi

Hiroshi Hamada

Tsutomu Ishikawa

Tsuyoshi Yamamoto

Noriko Watanabe

Yoshihiro Yoneda

Hiroaki Kato

Manabu Matsuda

Chikashi Anayama

Haruhisa Soda

Koji Otsubo

Makoto Kondo

Toshihiko Hirobe

Akira Fukushima

Toshio Takemoto

Hiroshi Ishikawa

Takuya Fujii

Takayuki Watanabe

Tadanori Hishida

Hisato Nagatomi

Tatsuroh Ikeda

A method of manufacturing a distributed feedback semiconductor laser, has the steps of: growing on a semiconductor substrate a lamination of alternately stacked lower barrier layer and lower well layer having a band gap narrower than the lower barrier layer, to form a lower quantum well structure; growing an intermediate layer on an uppermost lower well layer, the intermediate layer having a band gap broader than the lower well and a thickness thicker than the lower barrier layer; growing on the intermediate layer a lamination of alternately stacked upper well layer and upper barrier layer having a band gap broader than the upper well layer and a thickness thinner than the intermediate layer, to form an upper quantum well structure; forming a mask on the upper quantum well structure, the mask having periodical pattern; by using the mask as an etching mask, etching the upper quantum well structure in a periodical shape by using the intermediate layer as an etching margin layer; and removing the mask. Complex coupling DFB lasers with a small variation in characteristics can be provided.

Complex coupling MQW semiconductor laser

An optical semiconductor element and an optical element having an optical coupling facet are disposed on a support surface of a platform. The optical element is optically coupled to the optical semiconductor element at the optical coupling facet. A protective member covers the optical semiconductor element and is disposed at least in a light transmission area in a space between the semiconductor element and the optical coupling facet of the optical element. The protective member is made of gel acrylic modification resin. An optical semiconductor module having a sufficient moisture resistance and being suitable for low cost is provided.

Optical semiconductor module, its manufacture, reflection film, its manufacture, and laser and optical devices using reflection film

A DFB laser in which a thickness of an active layer changes periodically and a greater part of current injected from external sides is selectively injected into the thick regions (projected regions) of the active layer. Therefore, the ratio of the gain coupling to the refractive index coupling can be further increased, and a threshold current can be lowered, and stability of single mode oscillation can also be improved.

Distributed feedback semiconductor laser

There is provided a semiconductor laser which comprises a first cladding layer formed of compound semiconductor having first conductivity type impurity and having a mesa-shaped projection, an active layer formed on the projection like a stripe and having side surfaces which are inclined at an angle of more than 70 degrees but less than 90 degrees relative to an upper surface of the first cladding layer, buried layers formed on both sides of the projection and having second conductivity type impurity, current blocking layers each having one end which contacts a virtual surface obtained by extending upward a side surface of the active layer and having a first facet which extends downward from the one end and is inclined by about 55 degrees relative to the upper surface of the first cladding layer and formed on each buried layer and having the first conductivity type impurity, and second cladding layers formed on the current blocking layers and the active layer and having the second conductivity type impurity.

Semiconductor laser and method of manufacturing the same

In a semiconductor light-emitting device including an MQW diffraction grating structure mainly used in a gain-coupled DFB laser, the ratio of the gain coupling coefficient to the index coupling coefficient is increased by making each well layer in MQW-A thicker than that in MQW-B. Each well layer and each barrier layer in the MQW structure are made of different compositions of GaInAsP. This implements a semiconductor light-emitting device with high wavelength stability, which does not induce any mode hop even during modulation with high output power or even when external optical feedback is present.

Semiconductor light-emitting device

A technique for manufacturing a semiconductor device includes the steps of preparing a stepped substrate made of a group III-V compound semiconductor and having a flat surface exposing a (1 0 0) plane and a slanted surface exposing an (n 1 1)B plane whrerein n is a real number of about 1.ltoreq.n, and epitaxially growing the group III-V compound semiconductor to form an epitaxial layer on the surface of the stepped substrate while doping p- and n-type impurities, selectively at the same time or, alternatively, under conditions such that the grown epitaxial layer has an n-type region on the slanted surface and a p-type region on the flat surface.

Semiconductor device and its manufacture utilizing crystal orientation

A technique for manufacturing a semiconductor device includes the steps of preparing a stepped substrate made of a group III-V compound semiconductor and having a flat surface exposing a (1 0 0) plane and a slanted surface exposing an (n 1 1)B plane, wherein is a real number of about 1.ltoreq.n, and epitaxially growing the group III-V compounds semiconductor to form an epitaxial layer on the surface of the stepped substrate while doping p- and n-type impurities, selectively at the same time or, alternatively, under conditions such that the grown epitaxial layer has an n-type region on the slanted surface and a p-type region on the flat surface.

Method of making a semiconductor device utilizing crystal orientation

An optical transmission and reception device comprises an optical transmission region including an active layer which oscillates and outputs laser beam of a wavelength .lambda.1 on a transmission state, and guides received light of a wavelength .lambda.2 different from the wavelength .lambda.1 on a reception state and an optical reception region including a light detecting device for detecting the received light guided by the active layer and converting the received light into electric signals. The optical transmission and reception device having an optimum structure for the transmission and reception can be realized. Accordingly an optical transmission and reception device having good characteristics, which are suitably used in bidirectional communications by optical subscribers' systems, and optical parallel link data transmission in computers.

Optical transmission and reception device

The surface emitting laser of the present invention provided with a resonator has a structure in which a quantum well structure where a light absorption wavelength region is changed due to the Wannier-Stark effect or quantum-confinement Stark effect is formed in the non-doped Distributed Bragg Reflector mirror at the opposite side to a semiconductor substrate out of a pair of Distributed Bragg Reflector mirrors sandwiching the resonator.

Surface emitting laser provided with light modulator

A planar laser diode includes a substrate, a first multilayer structure on the substrate and formed of an alternate stacking of a first epitaxial layer and a second epitaxial layer, a cavity structure provided on the first multilayer structure and including an undoped active layer for producing optical radiation as a result of stimulated emission, a second multilayer structure provided on the cavity structure and formed of an alternate stacking of a third epitaxial layer and a fourth epitaxial layer, a first electrode structure on a bottom surface of the substrate, a second electrode structure for injecting carriers to said active layer via said cavity structure, an optical passage provided in one of the first and second electrode structures for allowing an optical beam to pass therethrough; a a current path structure provided between the second electrode structure and the active layer for providing a passage of the carriers, a current confinement structure for confining the passage of the carriers such that said carriers flow along a path generally coincident to an optical path of the optical beam, and a conductive region provided in contact with said the electrode structure for causing the carriers to flow therethrough, wherein the conductive region is provided so as to avoid the optical path.

Planar light emitting device having a reduced optical loss

A current constriction layer surrounding a vertical-cavity region is formed in a cladding layer of a surface emitting laser. The forbidden band width of the material forming this current constriction layer is wider than the forbidden band width of a material forming the cladding layer. Further, the current constriction layer and the cladding layer are formed of semiconductors, and conduction types thereof are different from each other. Further, the upper surface of the cladding layer covering the current constriction layer has a step in the periphery of vertical-cavity region.

Surface emitting laser and method of manufacturing the same

A thin film semiconductor device and a liquid crystal display apparatus are provided wherein the thin film semiconductor device having light irradiated thereon is cut off by a conductor layer, and the ight can be prevented from reaching the semiconductor layer. As a result, the generation of carriers due to optical excitation does not occur and the off current can be reduced. Because there is no area where electric field intensity in an opposed direction to the source electrode and the drain electrode is weaker than the electric field intensity of the channel region in the semiconductor layer, even after an operation for a prolonged duration under the irradiation of light, carriers generated by optical excitation are not accumulated in the semiconductor layer, and the probability of trapping for the carriers into a gate insulating film is quite low, and therefore variations in the characteristics of the thin film semiconductor device are negligibly small. The liquid crystal display apparatus using the thin film semiconductor can restrict such deteriorations of display quality as the degradation of contrast and uniformity.

Thin film semiconductor device and liquid crystal display apparatus

A thin-film transistor array has an insulating substrate; a plurality of thin-film transistors disposed in a matrix form on the substrate; a plurality of gate bus lines formed parallel to each other on the substrate, each of the gate bus lines being connected electrically with the gate electrodes of the thin-film transistors in the corresponding row of the matrix; and a plurality of source bus lines formed perpendicular to the gate bus lines on the substrate, each of the source bus lines being connected electrically with the source electrodes of the thin-film transistors in the corresponding column of the matrix; wherein at the intersections of the gate bus lines and the source bus lines, there is disposed a layered structure between the gate bus line and the source bus line, having successively a gate insulating film, a first semiconductor film, a protective insulating film, and a second semiconductor film which is connected electrically with the source intersections, wherein the width of the protective insulating film in the direction in which the gate bus line extends is equal to or greater than that of the second semiconductor film in that direction.

Thin-film transistor array

A thin film semiconductor device and a liquid crystal display apparatus is provided wherein the thin film semiconductor device having light irradiated thereon is cut off by a conductor layer, and the light can be prevented from reaching the semiconductor layer. As a result, the generation of carriers due to optical excitation does not occur and the off current of the device can be reduced. Because there is no area where the electric field intensity in an opposed direction to the source electrode and the drain electrode is weaker than the electric field intensity of the channel region in the semiconductor layer, even after operating the device for a prolonged duration under the irradiation of light, carriers generated by optical excitation are not accumulated in the semiconductor layer, and the probability of trapping the carriers into a gate insulating film is quite low, and therefore variations in the characteristics of the thin film semiconductor device are negligibly small. The liquid crystal display apparatus using the thin film semiconductor can restrict such deteriorations of display quality such as the degradation of contrast and uniformity.

Growing community of inventors

Kawasaki, Japan

Hajime Shoji