Abstract:
A semiconductor light-emitting diode (LED), which is substantially transparent to its own generated radiation, is coated with a reflecting layer having an exit aperture for transmission of optical radiation, for example, to an optical fiber. The reflecting layer includes a layer of dielectric in contact with the semiconductor, the dielectric layer itself being coated with an optically reflecting metal layer. The dielectric layer is made sufficiently thick to prevent the evanescent waves (of the totally internally reflected light in the semiconductor) from contacting the metal, thereby affording very close to 100 percent optical reflection of the optical rays in the semiconductor which are incident on the dielectric at greater than the critical angle. In addition, a significant portion of the semiconductor-dielectric interface is rough, thereby scattering (randomizing) the totally internally reflected rays in the semiconductor, which rays otherwise would have no chance of being accepted into the optical fiber. Thus, the overall coupling efficiency of optical radiation from the diode to the optical fiber is enhanced.
Abstract:
Gallium arsenide power dissipating devices are described, which comprise an array of mesas formed on a plated heat sink in order to reduce thermal effects. The array is connected in parallel with beam leads to permit thermocompression bonding to only one of the mesas and thus reduce the number of bonding operations. Bonding stresses to the device may be eliminated by rendering one of the mesas inactive.
Abstract:
A method for precisely tailoring the thickness of a layer of semiconductor material in a structure comprising regions of varying doping concentrations in order to achieve desired uniform electrical properties. The method involves, generally, electrolytically thinning the layer to remove the semiconductor material until a desired field distribution in the structure is reached. In one embodiment, an FET with an epitaxial layer on a semi-insulating substrate is manufactured by successively oxidizing the epitaxial layer and dissolving the oxide until the depletion region resulting from the applied potential extends into the semi-insulating substrate and oxide growth stops. This results in a uniform pinch-off condition along the layer regardless of the original non-uniformity in the epitaxial layer. In a further embodiment, the epitaxial layer in an IMPATT structure is thinned by successive oxidation and dissolution until the voltage dropped across the semiconductor is equal to the applied potential and again oxide growth stops. This procedure results in a desired uniform breakdown voltage for the wafer.