Hitachi, Ltd.

Masaaki Sawai

Hiroshi Naka

Masamichi Kobayashi

Shoji Hayashi

Masahiro Ichiki

A semiconductor laser chip having a buried hetero structure comprising a semiconductor substrate and a light emitting portion wherein the active layer and buried layers of the light emitting portion are disposed to be on only a portion of the semiconductor substrate. By virture of this arrangement, the probability of occurrence of V.sub.TH effects can be reduced. Also, the occurrence of the junction short-circuits resulting from an overhanging electrode or from deposition of foreign matter can be reduced.

Semiconductor laser chip having a layer structure to reduce the

A light emitting device is disclosed which includes a semiconductor block, an active layer disposed in such a fashion as to penetrate through the mutually facing end surfaces of the semiconductor block, and an electrode disposed on the main plane of the semiconductor block, wherein the electrode consists of a first electrode portion disposed along the active layer, and a second electrode portion continuing integrally the first electrode portion and having the periphery thereof out of contact from the periphery of the second main plane of the semiconductor block. A current is caused to uniformly flow through the entire active layer, and a light emitting operation is carried out stably. Since the electrode is not disposed on the periphery of the semiconductor block, the occurrence of junction short-curcuit, which might otherwise occur when a wafer is cut off to produce laser chips or when the corners of the chip break off, can be reduced.

Light emitting device with improved electrode structure to minimize

A semiconductor laser chip having a buried heterostructure comprising a semiconductor substrate and a light emitting portion wherein the active layer and buried layers of the light emitting portion are disposed to be on only a portion of the semiconductor substrate. By virtue of this arrangement, the probability of occurrence of V.sub.TH effects can be reduced. Also, the occurrence of the junction short-circuits resulting from an overhanging electrode or from deposition of foreign matter can be reduced.

A light emitting device is disclosed which includes a semiconductor block, an active layer disposed in such a fashion as to penetrate through the mutually facing end surfaces of the semiconductor block, and an electrode disposed on the main plane of the semiconductor block, wherein the electrode consists of a first electrode portion disposed along the active layer, and a second electrode portion continuing integrally the first electrode portion and having the periphery thereof out of contact from the periphery of the second main plane of the semiconductor block. A current is caused to uniformly flow through the entire active layer, and a light emitting operation is carried out stably. Since the electrode is not disposed on the periphery of the semiconductor block, the occurrence of junction short-circuit, which might otherwise occur when a wafer is cut off to produce laser chips or when the corners of the chip break off, can be reduced.

A semiconductor laser device is provided including semiconductor laser element, a PN-junction element which is used for temperature detection, and a thermoelectric heat pump which is electrically connected to the PN-junction element. According to this arrangement, heat developing from the semiconductor laser element is sensed by exploiting the fact that the forward voltage V.sub.F of the PN-junction element or PN-junction diode changes in correspondence with the change of the ambient temperature (this phenomenon itself is a matter already known), and the change of the forward voltage V.sub.F is fed back to the thermoelectric heat pump. Therefore, even when the semiconductor laser device is placed in the condition of a very high ambient temperature (open air temperature), the semiconductor laser element is cooled down to a predetermined temperature by the thermoelectric heat pump so as to produce a prescribed optical power at all times. Thus, the semiconductor laser element itself is driven in an appropriate temperature condition (for example, 25.degree. C.), so that the degradation of the semiconductor laser element can be prevented.

Growing community of inventors

Takasaki, Japan

Masaaki Sawai