Sharp Kabushiki Kaisha Corporation

Tetsurou Murakami

Takahisa Kurahashi

Hiroshi Nakatsu

Hiroyuki Hosoba

Shouichi Ohyama

Osamu Yamamoto

Shouichi Ooyama

A semiconductor light emitting device includes a first conductivity-type first semiconductor layer; an emission layer; a second conductivity-type second semiconductor layer; and a second conductivity-type transparent substrate transparent to light beams from the emission layer and directly bonded to the second semiconductor layer. The transparent substrate has a parallel surface almost parallel to the emission layer on an opposite side of the emission layer, and an inclined surface adjoining the parallel surface and inclined to the parallel surface. Light beams totally reflected on the parallel surface and light beams totally reflected on a side surface of the transparent substrate come incident to the inclined surface at an angle smaller than the critical angle, and emit out of the semiconductor light emitting device.

Semiconductor light emitting device having a current narrowing portion and manufacturing method for semiconductor light emitting device

On a GaAs substrate (), are formed a DBR (Distributed Bragg Reflector) (), and a light-emitting layer () made of a plurality of layers of AlGaInP (0&#x2266;y&#x2266;1, 0&#x2266;z&#x2266;1) above the DBR (). A semiconductor layer or a plurality of semiconductor layers ()-() having a number of layers of 1 or more are formed on the light-emitting layer (), and a grating pattern for scattering light is formed on a surface of the semiconductor layer () by photolithography and by etching with a sulfuric acid/hydrogen peroxide based etchant. Thus, a semiconductor device small in radiation angle dependence of light emission wavelength, as well as a manufacturing method therefor, are provided.

Semiconductor light-emitting device and manufacturing method therefor

An n-type AlAs/n-type AlGaAs DBR layer and a p-type (AlGa)InP/p-type AlInP DBR layer are formed on an n-type GaAs substrate at specified intervals so that a reflection spectrum is centered at 650 nm and the resonance wavelength becomes 650 nm. A quantum well active layer (light-emitting layer) is formed so that the light emission peak wavelength becomes 650 nm in the belly position of the standing wave generated in a resonator constructed of both the DBR layers. A grating pattern is formed on the surface of a p-type AlGaAs light diffusion layer that serves as a light-emitting surface surrounded by a p-type electrode. By thus roughening the light-emitting surface, light emitted from the light-emitting layer is diffused in various directions, reducing the radiation angle dependency of the emission light wavelength.

Semiconductor light-emitting device and method for fabricating the device

There is provided and manufactured, at a low cost and with high yields, a semiconductor light emitting device which allows extraction of light produced in an emitter layer not only from its top surface but also from its side surfaces and which has high luminance. An AlGaInP-based semiconductor light emitting device having a contact layermade of (AlGa)InP (0&#x2266;y&#x2266;1, 0&#x3c;z&#x3c;1) disposed between an emitter layerand a transparent substratewhich is transparent to emission wavelengths from the emitter layer

Semiconductor light emitting device and method for manufacturing same

A semiconductor light emitting device has in sequence on a semiconductor substrate, a multilayer reflection film, a semiconductor layer, and a quantum well active layer. A distance between an upper surface of the multilayer reflection film and a lower surface of the quantum well active layer is 2&#x3bb;/n or less, where &#x3bb; is a light emission wavelength and n is an average refractive index of the semiconductor layer disposed in between the multilayer reflection film and the quantum well active layer. A phase difference between a reflected ray of light reflected by the multilayer reflection film and an emitted ray of light from the quantum well active layer is a multiple of 2&#x3c0;. The semiconductor light emitting device stably obtains a specified peak wavelength even when there is slight variance in the distance between the upper surface of the multilayer reflection film and the lower surface of the quantum well active layer.

Semiconductor light emitting device for stably obtaining peak wave length of emission spectrum

A semiconductor light-emitting device includes an active layer having a single quantum well structure. The single quantum well structure enables a high-speed response such that the rise and fall time is 2.1 nsec. Further, the single quantum well active layer is doped with Zn at a concentration of 8&times;10 cm . Thereby, the half-value width of the light-emitting spectrum is 25 nm or more, which is wider than in the case of no doping. Thus, temperature dependence of an optical output is reduced.

Semiconductor light-emitting device

A resonant cavity type light emitting diode has a first DBR made of n-type AlAs or Al Ga As, a quantum well active layer, a second DBR made of p-type (Al Ga ) In P or Al In P, and an n-type current constriction layer on an n-type GaAs substrate. The first DBR and the second DBR form a resonator. The quantum well active layer is formed in a position of an antinode of a standing wave inside the resonator. Between the second DBR and the current constriction layer, there is provided a p-type GaP etching protection layer that has a value obtained by dividing resistivity by thickness being 1&times;10 &OHgr; or more. Since a current in a current flow pass formed in the current constriction layer hardly diffuses to the outside of the current flow pass, there is generated few region with low current density that causes deterioration of responsespeed in a quantum well layer. Thus, the light emitting diode has an excellent high-speed response.

Semiconductor light emitting device

Is provided a resonant cavity type light emitting diode having excellent humidity durability and a light output unsaturated even several 10 mA., which is suitable for mass production. The semiconductor light emitting element has a resonator formed by one set of multi-layer reflecting films disposed at a constant distance on a GaAs substrate inclined at an angle of not less than 2 degrees in the direction &lsqb;011&rsqb; or &lsqb;0-1-1&rsqb; from the plane ( ) and a light emitting layer disposed at a loop position of a standing wave in the resonator, wherein a multi-layer reflecting film disposed on the GaAs substrate side is composed of plural layers of Al Ga As (0 &lE;x&lE;1) and a multi-layer reflecting film disposed on the opposite side of the GaAs substrate is composed of plural layers of Al Ga In P (0&lE;y&lE;1, 0&lE;z&lE;1), thereby achieving an improved humidity durability and an increased reflection factor by increasing the number of the reflection layers.

Semiconductor light emitting element

An n-type AlAs/n-type Al Ga As DBR layer and a p-type (Al Ga ) In P/p-type Al In P DBR layer are formed on an n-type GaAs substrate at specified intervals so that a reflection spectrum is centered at 650 nm and the resonance wavelength becomes 650 nm. A quantum well active layer (light-emitting layer) is formed so that the light emission peak wavelength becomes 650 nm in the belly position of the standing wave generated in a resonator constructed of both the DBR layers. A grating pattern is formed on the surface of a p-type Al Ga As light diffusion layer that serves as a light-emitting surface surrounded by a p-type electrode. By thus roughening the light-emitting surface, light emitted from the light-emitting layer is diffused in various directions, reducing the radiation angle dependency of the emission light wavelength.

A light-emitting diode having an excellent high-speed response characteristic and capable of giving a large light output with a small variation of the light output during the operation is provided. In the light-emitting diode, an active layer comprising a single quantum well layer of p-type Ga In P, a lower barrier layer of p-type (Al Ga ) In P and an upper barrier layer of p-type (Al Ga ) In P is highly doped with p-type dopant (Zn, Mg, Be, C) or n-type dopant (Si, Se, Te) to produce non-radiative recombination level in the upper and lower barrier layers. Carriers injected into the quantum well layer not only recombine radiatively therein and also recombine nonradiatively at boundaries of the upper barrier layer and the lower barrier layer, remarkably increasing recombination velocity of carriers and dramatically improving the response characteristic.

Light-emitting semiconductor element

The present invention relates to a semiconductor light-emitting device used for optical transmission (particularly for IEEE 1394) and displays and the like. More specifically, an object of the present invention is to provide a semiconductor light-emitting device capable of emitting the light with a high efficiency by extending a distance from an active layer to a boundary having poor crystal quality due to Group V elements As and P exchange to suppress deterioration in crystal quality of the active layer. According to the present invention, a semiconductor light-emitting device capable of emitting the light with a high efficiency because a reflecting multilayer with a different material system from that of an active layer is formed on the substrate in order to achieve a high reflectance, however, the active layer is formed, after a reflecting multilayer formed with the same material system as that of the active layer is formed thereon, to lengthen a distance between the active layer and a material system exchange boundary.

A semiconductor light emitting device has in sequence on a semiconductor substrate, a multilayer reflection film, a semiconductor layer, and a quantum well active layer. A distance between an upper surface of the multilayer reflection film and a lower surface of the quantum well active layer is 2&lgr;/n or less, where &lgr; is a light emission wavelength and n is an average refractive index of the semiconductor layer disposed in between the multilayer reflection film and the quantum well active layer. A phase difference between a reflected ray of light reflected by the multilayer reflection film and an emitted ray of light from the quantum well active layer is a multiple of 2&pgr;. In an emission spectrum of the semiconductor light emitting device, two troughs caused by interference between the emitted ray of light and the reflected ray of light appear in the both sides of a main peak. Therefore, the troughs are unlikely to match the main peak, and the peak wavelength of the semiconductor light emitting device can be sustained. Thus, the semiconductor light emitting device stably obtains a specified peak wavelength even when there is slight variance in the distance between the upper surface of the multilayer reflection film and the lower surface of the quantum well active layer.

A light emitting diode comprising a multiple quantum well (MQW) layer as an active layer and a reflecting layer below the active layer, wherein the number and/or total thickness of well layers in the MQW layer is determined such that the MQW layer shows an external quantum efficiency higher than that of an MQW layer including a single well layer.

Light emitting diode

On an n-GaP substrate transparent against a radiation light of an InAlGaP based semiconductor element, a lattice distortion relaxation layer, a clad layer , an active layer, and a clad layer are created with InAlGaP. On top of the layers, there is formed an In Ga P current diffusion layer with In composition ratio x equal to (0<X<1). Through these steps, uneven depth on the crystal surface is decreased and crystal defect concentration is lowered. In addition, the energy gap of the current diffusion layer is made larger than the energy gap of the active layer, so that the GaP substrate and the uppermost InGaP current diffusion layer become transparent against a radiation light from the active layer, resulting in increased light emitting efficiency. Further, simple formation of layers from the lattice distortion relaxation layer to the current diffusion layer in sequence enables reduction of the production costs.

Growing community of inventors

Tenri, Japan

Tetsurou Murakami