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US 5,208,820 AGranted
Optical device with low-resistive multi-level reflecting structure
AssigneeNEC Corporation
InventorsKaori Kurihara, Mitsunori Sugimoto
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Abstract
An optical device has a multi-layer reflecting structure provided in association with an active layer for allowing light to oscillate, and the multi-layer reflecting structure is implemented by a plurality of units each having a high refractive film, a low refractive film and a layer for improving conductivity of the multi-layer reflecting structure, wherein the layer is implemented by a heavily doped impurity region with an impurity profile tracing plots of a delta function or by a quasi-graded super-lattice film microscopically graded in composition between the high and low refractive films.
Claims10
An optical device fabricated on a substrate, comprising:
- a) an active layer provided for light;
- b) a lower multi-layer reflecting structure provided on one side of said active layer, and having a plurality of combinations each implemented by an n-type low refractive film and an n-type high refractive film different in refractive index as well as in energy band gap;
- c) an upper multi-layer reflecting structure provided on the opposite side of said active layer, and having a plurality of combinations each implemented by a p-type low refractive film and a p-type high refractive film different in refractive index as well as in energy band gap;
- and
- d) a pair of electrodes operative to apply bias voltage across said lower and upper multi-layer reflecting structures to said active layer for producing light, at least one of said n-type low refractive film and said p-type low refractive film having a heavily doped region extending from a first heterojunction negatively biased toward a second heterojunction on the opposite side thereof in case of said n-type low refractive film or from said second heterojunction positively biased toward said first heterojunction in case of said p-type low refractive film, said heavily doped region having an impurity profile substantially tracing plots of a delta function.
2 more elements
An optical device fabricated on a substrate having atomic steps formed at intervals on a major surface thereof and terrace portions each extending over one of said intervals, comprising:
- a) a lower multi-layer reflecting structure of a first conductivity type grown on said major surface, and implemented by a plurality of semiconductor microstructures, each of said semiconductor microstructures having a high refractive film formed of a first compound semiconductor material mainly composed of a first element and a second element, a low refractive film formed of a second compound semiconductor material mainly composed of said second element and a third element, and a quasi-graded super-lattice layer inserted between said high refractive film and said low refractive film, and formed of a third compound semiconductor material mainly composed of said first to third elements, said atomic steps and said terrace portions being sequentially transferred to a surface of each high refractive film, to a surface of each quasi-graded super-lattice layer and to a surface of each low refractive film, said quasi-graded super-lattice layer being implemented by a plurality of non-inverted mesa-shaped micro-stripes of said first compound semiconductor material interdigitated with a plurality of inverted mesa-shaped micro-stripes of said second compound semiconductor material, each of said non-inverted mesa-shaped micro-stripes projecting from one of said terrace portions on said surface of said high refractive film in such a manner that the width thereof is gradually decreased, each of said inverted mesa-shaped micro-stripes interdigitated between two of said non-inverted mesa-shaped micro-stripes projecting in such a manner that the width thereof is gradually increased;
- b) an active structure for light formed on said lower multi-layer reflecting structure;
- c) an upper multi-layer reflecting structure formed on said active structure, and having a second conductivity opposite to said first conductivity;
- and
- d) a pair of electrodes for applying bias voltage across said lower and upper multi-layer reflecting structures to said active structure.
2 more elements
A multi-layer reflecting structure fabricated on a substrate and applied with bias voltage for producing light, comprising:
- a plurality of combinations each having
- a) a low refractive film, and
- b) a high refractive film different in refractive index as well as in energy band gap from said low refractive film, said low refractive film having a heavily doped region extending from a first heterojunction negatively biased toward a second heterojunction on the opposite side thereof in case of n-type conductivity or from said second heterojunction positively biased toward said first heterojunction in case of p-type conductivity.
A quasi-graded super-lattice structure fabricated on a substrate having atomic steps at intervals and terrace portions each extending over one of said intervals, comprising:
- a high refractive film formed of a first compound semiconductor material mainly composed of a first element and a second element, a low refractive film formed of a second compound semiconductor material mainly composed of said second element and a third element, and a quasi-graded super-lattice layer inserted between said high refractive film and said low refractive film, and formed of a third compound semiconductor material mainly composed of said first to third elements, said atomic steps and said terrace portions being sequentially transferred to a surface of each high refractive film, to a surface of each quasi-graded super-lattice layer and to a surface of each low refractive film, said quasi-graded super-lattice layer being implemented by a plurality of non-inverted mesa-shaped micro-stripes of said first compound semiconductor material, each of said non-inverted mesa-shaped micro-stripes projecting from one of said terrace portions on said surface of said high refractive film in such a manner that the width thereof is gradually decreased, each of said inverted mesa-shaped micro-stripes interdigitated between two of said non-inverted mesa-shaped micro-stripes projecting in such a manner that the width thereof is gradually increased.
Dependencies are inferred from the claim text.