Mitsubishi Denki Kabushiki Kaisha

Shigeru Mitsui

Ryo Hattori

Saburo Takamiya

Tetsuya Yagi

Kazuhisa Takahashi

Manabu Wataze

Teruyuki Shimura

Hiroaki Morikawa

Satoshi Arimoto

Takuji Sonoda

Mikio Deguchi

Hisao Kumabe

Yoshitatsu Kawama

Hideo Naomoto

Satoshi Hamamoto

A bipolar transistor circuit element includes a semiconductor substrate; successively disposed on the substrate, a base layer, an emitter layer, and a collector layer; a bipolar transistor formed from parts of the collector, base, and emitter layers and including a base electrode electrically connected to the base layer and a base electrode pad for making an external connection to the base layer; a base ballasting resistor formed from a part of the base layer isolated from the bipolar transistor and electrically connecting the base electrode to the base electrode pad; and a base parallel capacitor connected in parallel with the base ballasting resistor wherein the base parallel capacitor includes part of the base input pad, a dielectric film disposed on part of the base electrode pad, and a second electrode disposed on the dielectric layer opposite the base electrode pad and electrically connected to the emitter electrode of the bipolar transistor. The base ballasting resistor has a high resistance relative to an emitter ballasting reactor so that it can be easily mass produced with good uniformity and yield.

Bipolar transistor circuit element having base ballasting resistor

In a method for fabricating a thin film solar cell, a thin semiconductor film serving as a power generating layer is formed on a substrate via an intermediate layer, a plurality of holes are formed penetrating through the thin semiconductor film and reaching the intermediate layer, and the intermediate layer is etched away through the through-holes, separating the thin semiconductor film from the substrate with high-efficiency. Since stress is hardly applied to the thin semiconductor film during the separation process, cracking and breaking of the semiconductor film is avoided. Further, since the surface of the substrate is maintained in good condition, the substrate can be reused, resulting in a reduction in the production cost.

Method for producing thin film solar cell

A semiconductor laser particularly adapted for operation in the self-pulsation mode and method for production thereof. A central mesa is formed in the upper cladding layer and normally requires relatively thick sections at either side of the mesa in order to form a wageguide of sufficient thickness to cause self-pulsation operation. In order to control the thickness of the upper cladding layer bounding the mesa, the mesa is first formed by etching the regions bounding the mesa to relatively thin sections capable of ready gauging by optical interferometry. A composite upper clading layer is then formed by utilizing MOCVD crystal growth techniques to form a buffer layer on the upper cladding layer bounding the mesa, the buffer layer having an aluminum content about the same as the aluminum content of the AlGaAs upper cladding layer. The composite layer functions as a comparatively thick waveguide which can be formed to the necessary thickness with adequate accuracy to provide a high yield when producing self-pulsation lasers according to the present invention.

Method for production of a semiconductor laser

A semiconductor laser includes a first cladding layer having a forward mesa with at least one end at least partially spaced from the adjacent facet of the laser. A current blocking layer buries the mesa at its sides and at least partially at the ends of the mesa so that the ends are at least partially spaced from the facets. The current blocking layer reduces current injection and surface recombination at the facets at least partially spaced from the mesa ends, thereby increasing the catastrophic optical damage level of the laser. The mesa is formed without etching or exposing the active layer so that formation of interfaces that refract light or shorten laser lifetime are avoided. An increase in COD level of about 20 percent is achieved in the invention.

Method of making a semiconductor laser

A semiconductor laser particularly adapted for operation in the self-pulsation mode and method for production thereof. A central mesa is formed in the upper cladding layer and normally requires relatively thick sections at either side of the mesa in order to form a waveguide of sufficient thickness to cause self-pulsation operation. In order to control the thickness of the upper cladding layer bounding the mesa, the mesa is first formed by etching the regions bounding the mesa to relatively thin sections capable of ready gauging by optical interferometry. A composite upper cladding layer is then formed by utilizing MOCVD crystal growth techniques to form a buffer layer on the upper cladding layer bounding the mesa, the buffer layer having an aluminum content about the same as the aluminum content of the AlGaAs upper cladding layer. The composite layer functions as a comparatively thick waveguide which can be formed to the necessary thickness with adequate accuracy to provide a high yield when producing self-pulsation lasers according to the present invention.

Semiconductor laser

A semiconductor laser includes a first cladding layer having a forward mesa with at least one end at least partially spaced from the adjacent facet of the laser. A current blocking layer buries the mesa at its sides and at least partially at the ends of the mesa so that the ends are at least partially spaced from the facets. The current blocking layer reduces current injection and surface recombination at the facets at least partially spaced from the mesa ends, thereby increasing the catastrophic optical damage level of the laser. The mesa is formed without etching or exposing the active layer so that formation of interfaces that refract light or shorten laser life-time are avoided. An increase in COD level of about 20 percent is achieved in the invention.

A P type semiconductor layer is epitaxially grown on an N.sup.+ type semiconductor substrate to form a PN junction between them so as to expose its circumference to the peripheral surface of the substrate. The P type layer is formed into a mesa having a tilted surface to which the circumference of the PN junction is exposed. Then an N.sup.+ type diffusion layer is disposed on the tilted mesa surface to protect the PN junction.

Mesa type semiconductor device

An avalanche photodiode comprises a photo-electric conversion region made of a semiconductor having an energy band gap smaller than the photon energy and a carrier multiplying region made of a semiconductor that differs from the semiconductor of the photo-electric conversion region. The different semiconductors for imparting superior functions to the regions are used to improve the quantum efficiency in the photo-electric conversion region and to decrease noise in the carrier multiplying region.

Avalanche photodiode

A semiconductive body in the form of a rectangular parallelepiped is formed of a semiconductive material, such as gallium arsenide or indium phosphide or Group IV elements, having an electric field-to-current characteristic either including a nonlinear region, such as a negative resistance region; or nonlinear and partly including a saturated region. A dc biasing electric field is applied across two opposite faces of the substrate while an ac input electric field is applied across two opposite faces perpendicular to the first faces of the semiconductive body to form a resultant electric field variable in a portion of the characteristic including the nonlinear or saturated region. This variation in the resultant field causes a current component flowing in the direction of the biasing field through the body to have a frequency equal to a multiple of that of the ac input field.

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Itami, Japan

Shigeru Mitsui