At&t Bell Laboratories

Lucent Technologies Inc.

Robert S Freund

Kent D Choquette

Minghwei Hong

Greg E Blonder

Daryoosh Vakhshoori

Roderick Kent Watts

Joseph Petrus Mannaerts

Robert C Wetzel

This invention involves a vertical cavity surface emitting laser ('VCSEL') having a Group III-V semiconductor epitaxial mesa structure with an electrically insulating sidewall located on the mesa's sidewalls for confinement of the optical radiation generated in the laser. A suitably doped Group III-V epitaxial layer or a layer of insulating material such as silicon dioxide acts as the insulating sidewall layer. Advantageously, the structure has a self-aligned ohmic contact layer located everywhere on the top surface of the epitaxial mesa structure.

Vertical cavity semiconductor laser

The present applicants have discovered that one can make a surface emitting laser with enhanced optical confinement and improved heat sinking characteristics by etching away portions of the growth layers peripheral to the intended laser cavity and regrowing peripheral regions of material having a lower index of refraction than the active region. Using low damage etching and either in situ regrowth or hydrogen plasma cleaning followed by regrowth, a surface emitting laser having enhanced optical isolation and heat sinking characteristics can be made.

Semiconductor surface emitting laser having enhanced optical confinement

In accordance with the invention, a contaminated III-V semiconductor surface is cleaned by the sequential steps of exposure to hydrogen plasma, chemical etching in chlorine and annealing in vacuum. In a preferred embodiment, a semiconductor of the gallium arsenide family is subjected to hydrogen plasma in an ECR system for 20-120 minutes, then, without breaking vacuum, subjected to a Cl.sub.2 chemical etch at 250.degree. C.-450.degree. C. for 1-5 minutes. Again, without breaking vacuum, the semiconductor is annealed at 200.degree. C.-600.degree. C. for 5-15 minutes. To obtain good surface reconstruction, annealing preferably takes place at a temperature 300.degree. C. or above. The semiconductor surface thus processed is atomically smooth and sufficiently clean to permit regrowth of a high quality epitaxial layer.

Process for removing surface contaminants from III-V semiconductors

A light source, such as an LED, is provided with a multifaceted reflector to facilitate coupling of emitted light into an optical waveguide such as an optical fiber. In a preferred embodiment, a conventional LED fabricated on one side of a transparent substrate is provided with a series of integral concentric reflecting rings on the opposite side of the substrate. The rings reflect light diverging from the LED toward the central axis of an optical fiber light.

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Livingston, NJ, United States of America

Robert S Freund