Mitsubishi Denki Kabushiki Kaisha

Tomoko Kadowaki

Toshio Tanaka

Yutaka Mihashi

Takeshi Miura

Tohru Takiguchi

Norio Hayafuji

Hitoshi Tada

Akihiro Shima

Takashi Murakami

Kazuhisa Takagi

Toshitaka Aoyagi

Nobuyuki Tomita

Akira Takemoto

Yoshihiko Hanamaki

Syoichi Kakimoto

Yoriko Tanigami

A semiconductor laser device includes: an electrically insulating film on the top face of a laser chip; and a metal film, on the electrically insulating film. The electrically insulating film and/or the metal film has, in plan, a polygonal shape with five or more apexes, each of the apexes having an interior angle less than 180 degrees. Stress due to a change of temperature during operation is reduced, resulting in a semiconductor laser device having a longer life and higher reliability.

Semiconductor laser device

A ridge waveguide semiconductor laser includes an active layer, semiconductor layers on the active layer and having a ridge-shaped waveguide, an insulating film on the semiconductor layer, a first electrode layer in contact with the semiconductor layer through an opening in the insulating film, and a second electrode layer on the first electrode layer having a stripe shape and extending along the waveguide. A distance from an end face of a resonator of the laser to an edge of the second electrode layer does not exceed 20 &#x3bc;m.

Ridge waveguide semiconductor laser

A light modulator includes a semiconductor substrate having a main surface, a rear surface, and a grounding conductor on the rear surface. A wave guide section having a width is located on the semiconductor substrate. A bonding pad section on the semiconductor substrate is located adjacent to the wave guide section and an insulating layer covers the main surface of the semiconductor substrate. A portion of the insulating layer immediately opposite the bonding pad section includes a multiple layer structure of insulating films. An electrode opposite the bonding pad section is electrically connected to the wave guide section.

Light modulator

A light modulator having a reduced parasitic static capacitance includes a semiconductor substrate having a mesa section and a bonding pad section. A primary insulating film on the substrate continuously covers the mesa section and the bonding pad section. After a mask has been formed on a portion of the primary insulating film opposite the bonding pad section, the remaining portion of the primary insulating film is etched, followed by removal of the mask. After the removal of the mask, a second insulating film is formed continuously covering the primary insulating film opposite the bonding pad section and the mesa section so that a relatively thick insulating layer is present only opposite the bonding pad section.

Light modulator and method of manufacturing the light modulator

A semiconductor laser device includes a ridge waveguide having two side surfaces, a crystalline burying layer disposed at both side surfaces of the ridge waveguide, and a second conductivity type contact layer disposed on the burying layer and the ridge waveguide. The burying layer includes a first conductivity type first current blocking layer in contact with the side surfaces of the ridge waveguide, a second conductivity type second current blocking layer disposed on a portion of the first current blocking layer and separated from the ridge waveguide by a portion of the first current blocking layer near the ridge waveguide, a first conductivity type third current blocking layer disposed on a portion of the first current blocking layer near the ridge waveguide and on the second current blocking layer, and a second conductivity type final burying layer disposed on the third current blocking layer. In this structure, there is no pn junction at a regrowth interface between the final burying layer and the contact layer so that reduction in the forward voltage of the pn junction in continuous operation is avoided and increasing leakage current is suppressed so that the threshold current and light output of the laser do not deteriorate over time.

In accordance with the invention, after a crystal growth is carried out successively to produce at least a first conductivity type lower cladding layer, an active layer, a second conductivity type first upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, an etching stopper layer of AlGaAs having an AlAs composition ratio of more than 0.6, and a second conductivity type second upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, the second upper cladding layer is selectively etched using an etchant including an organic acid and hydrogen peroxide, thereby forming a ridge. As a result, a ridge-type semiconductor laser device which has a desirable laser structure and an oscillation wavelength below 830 nm can be produced easily with improved controllability and reproducibility.

Method for producing semiconductor laser device using etch stop layer

In accordance with the invention, after a crystal growth is carried out successively to produce at least a first conductivity type lower cladding layer, and active layer, a second conductivity type first upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, an etching stopper layer of AlGaAs having an AlAs composition ratio of more than 0.6, and a second conductivity type second upper cladding layer of AlGaAs having an AlAs composition ratio of 0.38 to 0.6, the second upper cladding layer is selectively etched using an etchant including an organic acid and hydrogen peroxide, thereby forming a ridge. As a result, a ridge-type semiconductor laser device which has a desirable laser structure and an oscillation wavelength below 830 nm can be produced easily with improved controllability and reproducibility.

Semiconductor laser including an aluminum-rich AlGaAs etch stopping layer

A semiconductor laser includes a p type cladding layer and an n type cladding layer sandwiching an active layer serially disposed on a semiconductor substrate. The p type cladding layer includes a first dopant impurity producing p type conductivity and a smaller quantity of a second impurity that produces n type conductivity and ionically bonds to the first impurity. The first and second dopant impurities attract each other and cannot move individually during a crystal growth step at high temperature whereby the diffusion of those impurities into the active layer is suppressed, preventing formation of a deep impurity level in the active layer, resulting in a semiconductor laser with a reduced threshold current.

Semiconductor laser

A semiconductor laser device producing visible light includes a double heterojunction structure having a first conductivity type lower cladding layer, an active layer and a second conductivity type upper cladding layer, formed in a first epitaxial growth process of AlGaInP series materials and a contact layer formed in a second or later epitaxial growth process. The contact layer is In.sub.x GA.sub.1-x As.sub.y P.sub.1-y which can be grown at a lower temperature than used in the first process. Therefore, deterioration in laser characteristics due to the diffusion of dopant impurities during the growth of contact layer can be prevented, resulting in a semiconductor laser device having high performance and long lifetime.

Growing community of inventors

Itami, Japan

Tomoko Kadowaki