The Furukawa Electric Co., Ltd.

Michinori Irikawa

Masayuki Iwase

Kazuaki Nishikata

Hitoshi Shimizu

Kenichi Iga

Yoshiyuki Hirayama

Takehiko Nomura

Jingming Xu

Toru Fukushima

Yuji Hiratani

Tetsuro Ijichi

Ranjit S Mand

Randit S Mand

A waveguide type semiconductor photodetector comprises a n-InP substrate, and a laminate including a first and second optical confinement layers and an undoped optical absorption layer interposed therebetween. The optical absorption layer has a thickness between 0.2 and 0.5 .mu.m, and a bandgap wavelength smaller than the bandgap wavelength of the first and second optical confinement layers. The photodetector has a large mode field diameter and a small coupling loss between the same and a glass fiber.

Waveguide type semiconductor photodetector

A field effect transistor having an excellent transfer conductance and an improved gate leakage current and breakdown voltage is provided. In the transistor, a multiquantum barrier structure 4 is arranged between a gate and a channel layer 3 along a channel layer 3 and having an effect of reflecting incident overflowing carriers a s waves in with with phase conditions of total reflection allowing mutual enhancement of the incident and reflected wave in a region between a channel layer 3 and a gate electrode 10 and/or in a region opposite to the gate electrode 10 relative to the channel layer 3.

Field effect transistor loaded with multiquantum barrier

Waveguide type light receiving element

The present invention provides a semiconductive light-emitting device involving a light-emitting layer of the multilayer strained quantum well structure that has a plurality of quantum well layers and a plurality of barrier layers, where each of said quantum well layers is constituted of a semiconductive crystal subjected to intraplanar compressive strain; each of the barrier layers is constituted of semiconductor crystal of AlInAs, AlGaInAs or AlGaInAsP. For high differential gain, each quantum well layer is 6nm thick or less, and the summed quantum well layers measure 13 to 1000 nm in thickness. Likewise, the invented scheme produces a light-emitting device involving a light-emitting layer of the multilayer strain compensation quantum well structure that has a plurality of quantum well layers and a plurality of barrier layers, where each of said quantum well layers is constituted of a semiconductive crystal subjected to intraplanar compressive strain; each of the barrier layers is constituted of semiconductor crystal of AlInAs, AlGaInAs or AlGaInAsP. For high differential gain, each quantum well layer is 6nm thick or less, and the summed quantum well layers measure 13 to 1000 nm in thickness.

Semiconductive light-emitting device having strained MQW with AlGaInAs

There is provided a semiconductor device comprising a Schottky junction having a very low leakage current and a high forward voltage. The device comprises a Schottky junction realized by a semiconductor 4 and a metal 6 and a multiquantum barrier structure 5 disposed on the interface of said semiconductor 4 and said metal 6 and having an effect of reflecting incident carriers as waves �in phase conditions capable of allowing mutual enhancement of the incident and reflected waves!.

Multiquantum barrier Schottky junction device

A photo diode in which an optical absorption layer and a p-type semiconductor layer neighboring on each other are designed to be at almost the same valence band level (their offset not exceeding 0.05 eV). Preferably the optical absorption layer is a GaInAsP layer with an absorption edge wavelength of 1.65 to 1.55 .mu.m, and the p-type semiconductor layer and lattice-matching with the preceding semiconductor layer are each an AlGaInAs layer with an absorption edge wavelength of 1.55 to 1.30 .mu.m remaining shorter than that of the optical absorption layer.

Photo diode providing high-linearity signal current in response to light

Optical semiconductive device with inplanar compressive strain

Strained superlattice semiconductor photodetector having a side contact

There is provided a semiconductor optical device having remarkable features including a low threshold current, a high light emitting efficiency, a high and stable optical output, a fast modulation capability, a large gain characteristics, resistance against oxidization, a high quality and a high degree of processibility. The device comprises a pair of optical confinement layers 13, 17 and a pair of cladding layers 12 and 18 arranged on and under an active layer 15 to produce a SCH structure, at least one of said optical confinement layers 13 and 17 comprising multiquantum barrier (MQB) structures 14, 16 as part thereof. If the active layer 15 is of multiquantum well type, the barrier layer 15a of the active layer 15 also comprises a multiquantum barrier (MQB) structure. With such an arrangement, the barrier height of the barrier layer 15a and the optical confinement layers 13, 17 can be made very high relative to the active layer 15 (well layer 15b). Such a semiconductor optical device can effectively suppress any overflow of carriers from the active layer 15 (well layer 15b) into the optical confinement layers 13, 17 and further into the cladding layers so that it shows a low and stable threshold current, an enhanced optical output power, an improved high-speed modulation performance and a quick responsiveness.

Semiconductor optical device

To provide a Schottky junction device having a super-lattice arranged in the Schottky interface in order to secure a high Schottky barrier and at the same time showing a high speed response by resolving the phenomenon of piled-up holes at the upper edge of the valence band, while maintaining the height of the Schottky barrier. A Schottky junction device having a Schottky junction of a semiconductor and a metal and a superlattice on the interface of the semiconductor and the metal, wherein the upper edge of the valence band of said superlattice is varied to show a turn to a specific direction. The phenomenon of hole-piling up at the upper end of the valence band is resolved while maintaining the height of the Schottky barrier and consequently such a Schottky junction device shows an excellent high speed response.

Schottky junction device having a Schottky junction of a semiconductor

There is provided a strained superlattice light emitting device for emitting light with a wavelength band around 0.8 .mu.m that is free from polarization dependency or can emit light either in the TE or TM mode with an output level much higher than that of an ordinary bulk layer, regardless of the density of injected current or carriers. Such a device comprises an InP substrate 1 and a pair of latticematched cladding layers 2 and 6 arranged on the substrate 1 and including first and second conductive type Al(Ga) InAs layers and an active layer 4 sandwiched by the pair of cladding layers 2 and 6 and having a strained superlattice structure, wherein the well layers 4a and 4b of the active layer 4 strained superlattice structure are respectively a GaInAsP layer showing an inplane tensile strain of 0.3 to 3% relative to the substrate and a GaInAsP layer showing an in-plane compressive strain of 0.3 to 3% relative to the substrate and the barrier layer 4b of the strained superlattice structure comprises an AlGaInAs layer.

Strained superlattice light emitting device

A semiconductor laser device comprising a semiconductor substrate, a multi-layered double heterostructure having active layers, a pair of cladding layers, a ridged waveguide structure and a current confining structure formed between the semiconductor substrate and the active layer. With such an arrangement, injected current is narrowed not only on the side above the ridge of the active layer but also on the substrate side of the active layer to improve the threshold current and its current confinement performance. When the two lateral trenches of the ridge are embedded with resin layers, the ridge stripe width can be made narrow to improve the threshold current of the device. When the active layer is realized in a DCC structure having two active layers and having an intermediary clad layer sandwiched therebetween, the device will show a low threshold current circular beam divergence and stabilized thermal characteristics.

Semiconductor laser device

There is provide a method of manufacturing a compound semiconductor (MBE) that can make the substrate surface of the semiconductor highly clean and plane so that no impurity may be left between the substrate surface and the grown crystal layer. In the step of cleaning a substrate with MBE, the substrate surface is irradiated with V molecular beams that cannot be significantly deposited out of molecular beams to be used for the crystal growth step, said V molecular beams being irradiated under a condition of P.sub.1 .ltoreq.(P.sub.2 .times.1/2), where P.sub.1 is the pressure of V molecular beams and P.sub.2 is the pressure of molecular beams in the crystal growth step and the temperature of the substrate surface is raised by heating until stabilized group III surfaces appear on the substrate surface. A very cleanand smooth substrate surface can be obtained with such an arrangement. Harmful impurities can be completely eliminated from the interface of the substrate and the crystal. The formation of a buffer layer can be effectively prevented in the initial stages of crystal growth. In short, high-quality compound semiconductors can be produced on a reliable basis.

Method of manufacturing compound semiconductor

There is provided a semiconductor laser device capable of emitting a laser beam having stable transverse modes. A ridge type semiconductor laser device comprises an upper clad layer 15 left on its active layer to a thickness (d) between 0.25 and 0.50 m in order to ensure a stable production of fundamental transverse modes for laser operation and a rib-shaped clad layer 16 having a bottom width (W) between 2.0 .mu.m and 3.5 .mu.m and projecting from the upper clad layer in juxtaposition with the light emitting region of the active layer 13. When d and W are found within the respective ranges, the device emits a laser beam having stable transverse modes.

There is provided a semiconductor device comprising a current confinement structure capable of reducing leakage currents. The semiconductor device comprising a current confinement structure and a multiquantum barrier structure 10 disposed in said current confinement structure and having an effect of reflecting incident carriers as waves in phase conditions capable of allowing mutual enhancement of the incident and reflected waves.

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Yokohama, Japan

Michinori Irikawa