Rohm Co., Ltd.

National Institute of Advanced Industrial Science and Technology

Other

Tetsuhiro Tanabe

Ken Nakahara

Hidemi Takasu

Shigeru Niki

Paul Fons

Kakuya Iwata

Masayuki Sonobe

Norikazu Ito

Haruo Tanaka

Jun Ichihara

Hisayoshi Kitajima

An infrared element () which includes at least a light emitting layer forming portion () composed of, for example, a first conductivity type cladding layer (), an active layer (), and a second conductivity type cladding layer () for emitting infrared light, is formed on a semiconductor substrate (), and a red element () which includes at least a light emitting layer forming portion () composed of, for example, a first conductivity type cladding layer (), an active layer (), and a second conductivity type cladding layer () for emitting red light, is formed on the same semiconductor substrate (). And their second conductivity type cladding layers (and) are made of the same material. As a result, forming process of their ridge portions may be communized and both of the elements can be formed respectively, with a window structure capable of high output operation.

Monolithic semiconductor laser

There is disclosed a monolithic semiconductor laser which is provided with an AlGaAs based semiconductor laser element () and an InGaAlP based semiconductor laser element () formed on a semiconductor substrate (). The AlGaAs based semiconductor laser element () is composed of an infrared light emitting layer forming portion (), which has an n-type cladding layer (), an active layer () and a p-type cladding layer () formed so as to have a ridge portion, and a current constriction layer () provided on sides of the ridge portion, while the InGaP based semiconductor laser element () is composed of a red light emitting layer forming portion (), which has an n-type cladding layer (), an active layer () and a p-type cladding layer () formed so as to have a ridge portion, and a current constriction layer () provided on sides of the ridge portion. The current constriction layers of the both elements are made of the same material having a larger band gap than that of the active layer () of the red light emitting layer forming portion. Consequently, there can be obtained a monolithic semiconductor laser capable of high temperature and high output operation without increasing the number of processes of the growth.

A light emitting device includes a silicon substrate (), a silicon nitride film () formed on the surface of the silicon substrate (), at least an n-type layer (), () and a p-type layer (), () which are formed on the silicon nitride film () and also which are made of a ZnO based compound semiconductor, and a semiconductor layer lamination () in which layers are laminated to form a light emitting layer. Preferably this silicon nitride film () is formed by thermal treatment conducted in an atmosphere containing nitrogen such as an ammonium gas. Also, in another embodiment, a light emitting device is formed by growing a ZnO based compound semiconductor layer on a main face of a sapphire substrate, the main face being perpendicular to the C-face thereof. As a result, it is possible to obtain a device using a ZnO based compound with high properties such as an LED very excellent in crystallinity and having a high light emitting efficiency.

ZnO based compound semiconductor light emitting device and method for manufacturing the same

It has a structure in which an active layer () that emits light by electric current injection is sandwiched between an n-type cladding layer () and a p-type cladding layer () made of materials having a larger band gap than the active layer (), wherein the active layer () is made, for example, of CdZnO (0&#x2266;x&#x3c;1). It is further more preferable if the cladding layers (), () are made, for example, of MgZnO (0&#x2266;y&#x3c;1). This narrows the band gap of the ZnO materials, and an oxide semiconductor capable of being wet-etched, easy to handle with, and excellent in crystallinity can be used as a material for an active layer or a cladding layer of a semiconductor light emitting device such as a blue light emitting diode or a blue laser diode in which an active layer is sandwiched between cladding layers, so that a blue semiconductor light emitting device being excellent in light emission characteristics can be obtained.

Semiconductor light-emitting device and method for manufacturing the same

On the surface of a conductive substrate ( ) of GaAs, Ge, Si, etc., a semiconductor lamination section including a light emitting layer forming portion ( ) that has at least an n-type layer ( ) and a p-type layer ( ) made from a compound semiconductor of a Group III element and nitrogen and that is laminated so as to form a light emitting layer is formed through a buffer layer ( ) suitable for the substrate. As a result, a semiconductor light emitting device using a Group III nitride compound semiconductor, which is of a vertical type that allows electrodes to be taken out from both of the upper and lower surfaces of a chip, has superior crystalline properties with high light emitting efficiency, and exhibits cleavage, is obtained. Therefore, it is possible to easily mount a LD chip on a sub-mount having a good thermal conductivity, and consequently to prevent a reduction and degradation in the light emitting efficiency (differential quantum efficiency) due to heat.

Semiconductor luminous elements and semiconductor laser

A light source device for a laser beam printer in which a semiconductor laser is driven with a pulse current having a minimum pulse width at the ON time on the order of milliseconds or less is provided, wherein the semiconductor laser is formed so that either the rate of change at the rise portion of the pulse current becomes &plusmn;8% or less or the semiconductor laser is excited in a multiple mode in the vicinity of the threshold value of the oscillation, and the semiconductor laser oscillates in a single mode at a current separated from the threshold value, by adjusting of at least one of the width w of a stripe groove ( ) of the current block layer, the composition of clad layers ( ), the distance d between the current block layer ( ) and the active layer ( ), the composition of the current block layer ( ) and the formation of a light absorption layer into the current block layer ( ). As a consequence, in the case where the light source device for the laser beam printer is driven with a short drive pulse on the order of several hundred micro seconds, the light source device becomes such that a transient phenomenon is not generated at the time of the rise of the pulse and a stable light output can be obtained.

Light source device for laser beam printer

When a laminated semiconductor portion of nitride based compound semiconductor is formed so as to constitute a portion forming a light emitting layer forming portion on a sapphire substrate, the sapphire substrate has an off orientation angle having a tilt relative to an A axis or a M axis in such a way that 0.2&deg;&lE;&thgr;&equals;&lcub;&thgr; &plus;&thgr; &rcub; &lE;0.3&deg;, wherein 0&deg;&lE;&thgr; &lE;0.3&deg;, 0&deg;&lE;&thgr; &lE;0.3&deg;, when taking the angle tilted relative to the A axis as &thgr; and to the M axis as &thgr; , and the foregoing nitride based compound semiconductor layers are laminated onto the surface of the off-oriented C plane. Therefore, it is possible to attain a semiconductor light emitting device having the superior characteristic of light emitting by growing the nitride based compound semiconductor on a sapphire substrate with the degree of flatness high and furthermore to attain a semiconductor laser of a small threshold current by forming a cleavage surface finely while improving the degree of flatness by off-orienting a sapphire substrate.

Semiconductor light emitting device and semiconductor laser

A light emitting device includes a silicon substrate ( ), a silicon nitride film ( ) formed on the surface of the silicon substrate ( ), at least an n-type layer ( ), ( ) and a p-type layer ( ), ( ) which are formed on the silicon nitride film ( ) and also which are made of a ZnO based compound semiconductor, and a semiconductor layer lamination ( ) in which layers are laminated to form a light emitting layer. Preferably this silicon nitride film ( ) is formed by thermal treatment conducted in an atmosphere containing nitrogen such as an ammonium gas. Also, in another embodiment, a light emitting device is formed by growing a ZnO based compound semiconductor layer on a main face of a sapphire substrate, the main face being perpendicular to the C-face thereof. As a result, it is possible to obtain a device using a ZnO based compound with high properties such as an LED very excellent in crystallinity and having a high light emitting efficiency.

ZnO compound semiconductor light emitting element

A first GaN layer ( ) is formed on a substrate ( ), mask layer ( ) having opening parts ( ) are formed thereon, a second GaN layer ( ) is selectively grown in the lateral direction from the opening parts on the mask layer, and further a nitride type compound semiconductor layered part ( ) is so laminated as to form a light emitting layer. Recessed parts ( ) are formed in the upper face side of the mask layer. In other words, owing to the recessed parts in the upper face side of the mask layer, the second GaN type compound semiconductor layer ( ) is grown as to form approximately parallel gap ( ) between the bottom face of the second GaN type compound semiconductor layer and the mask layer. Further, it is preferable for the mask to be formed in a manner that the opening parts for exposing the seeds are not arranged only continuous in one single direction in the entire surface of the wafer type substrate. Consequently, a nitride type compound semiconductor light emitting device can be obtained while being provided with a low dislocation density and excellent light emitting efficiency and especially a semiconductor laser with a lowered threshold current value can be obtained.

Semiconductor light emitting device and method for manufacturing the same

Semiconductor light emitting device

A semiconductor laser device includes a substrate formed of GaAs. A lower electrode is formed on an underside of this substrate. The substrate has, on its top surface, a lower cladding layer, an active layer, a first upper cladding layer, an etch stop layer, a current restricting layer, a second contact layer and an upper electrode formed in this order. A second upper cladding layer is formed widthwise centrally of the current restricting layer. A first contact layer and an insulation film are formed on the second upper cladding layer. This insulation film blocks a current from flowing from the upper electrode to an end of an optical waveguide. Accordingly, a current non-injection region is provided at an end of the active layer or optical waveguide.

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Kyoto, Japan

Tetsuhiro Tanabe