摘要:
Aluminum nitride, AlN, layers are grown on silicon substrates using molecular beam epitaxial (MBE) growth. The AlN layer is initially grown by subjecting the silicon substrate to background ammonia followed by repetitively alternating the flux of 1) Al without ammonia and 2) ammonia without Al. After the surface of the silicon structure is sufficiently covered with AlN, the wafer is further subjected to a flux of ammonia and aluminum applied simultaneously to continue the epitaxial growth process. The process minimizes the formation of amorphous silicon nitride, SiNx, compounds on the surface of the substrate which form due to background nitrogen levels in the molecular beam epitaxial growth apparatus. A surface free of amorphous silicon nitride is necessary for formation of high quality AlN. The AlN layer may be further used as a buffer layer for AlGaN/GaN growth. After the AlN layer is grown on the silicon structure, the silicon structure may be subjected to a flux of Ga and nitrogen to form a layer of GaN.
摘要:
Several methods are used in novel ways with newly identified and viable parameters to decrease the peak transition energies of the pseudomorphic InGaAs/GaAs heterostructures. These techniques, taken separately or in combination, suffice to permit operation of light emitting devices at wavelengths of 1.3 .mu.m or greater of light-emitting electro-optic devices. These methods or techniques, by example, include: (1) utilizing new superlattice structures having high In concentrations in the active region, (2) utilizing strain compensation to increase the usable layer thickness for quantum wells with appropriately high In concentrations, (3) utilizing appropriately small amounts of nitrogen (N) in the pseudomorphic InGaAsN/GaAs laser structure, and (4) sue of nominal (111) oriented substrates to increase the usable layer thickness for quantum wells with appropriately high In concentrations. In all of the above techniques, gain offset may be utilized in VCSELs to detune the emission energy lower than the peak transition energy, by about 25 meV or even more, via appropriate DBR spacing. Gain offset may also be utilized in some forms of in-plane lasers. Increased temperature may also be used to decrease peak transition energy (and therefore the emission energy) by about 50 meV/100.degree. C. All these techniques are furthermore applicable to other material systems, for example, extending the emission wavelength for laser diodes grown on InP substrates. Additionally, structures which utilize the above techniques are discussed.
摘要:
Localized nonuniformities in semiconductor crystals are analyzed by scanning the semiconductor surface with an electron beam and detecting and analyzing the radiation that is generated at the semiconductor surface by the electron beam and which passes through the semiconductor crystal.
摘要:
An optical multiplexer that adjusts the wavelength response and compensates for temperature effects by using rotatable mirror. The wavelength response of the device is adjusted by aligning the mirror at a correct angle with respect to the surface terminating the optical waveguide grating. The temperature dependence of the index of refraction of the material comprising the waveguides is compensated for by rotating a reflecting surface of the mirror, the rotation based on differential thermal expansion. Some exemplary embodiments may comprise a slab waveguide on a substrate (the slab waveguide having a first and second arcuate end surfaces) attached to a submount, a mirror assembly rigidly attached to the submount (the mirror assembly comprising a first and second materials having different coefficients of thermal expansion), and an optical waveguide grating (upon the substrate attached to the submount) optically coupled between the second arcuate surface and the mirror assembly. A portion of the mirror assembly between the reflector surface and where the mirror assembly is rigidly attached to the submount deforms as a function of temperature to change an angle between the optical waveguide grating and the reflecting surface.
摘要:
Methods of fabricating solid state optical waveguide structures comprising a doped silicon dioxide core layer sandwiched between lower and upper doped silicon dioxide cladding layers on a silicon substrate. The core and upper cladding layers are deposited using a plasma enhanced CVD process. The core layer is patterned to define one or more waveguide cores. The lower cladding layer is preferably also deposited using a plasma enhanced CVD process but alternatively may be formed by thermal oxidation.
摘要:
An optical waveguide structure comprising an annealed phosphorous doped silicon dioxide core surrounded by silicon dioxide cladding layers on a silicon substrate. The refractive index of the core exceeds the refractive index of the cladding to enable waveguiding of optical signals in the core. The upper cladding layer, and in one embodiment also the lower cladding, comprises high boron and phosphorous doped silicon dioxide, suitably doped with greater than about 9% of boron and with about 2.5% to 3.5% phosphorous to obtain a thermal coefficient of expansion approximating that of the silicon substrate. In an alternative embodiment, the lower cladding layer comprises thermally grown silicon dioxide, preferably including an upstanding pedestal on which the waveguide core extends. Advantageously, the cladding composition enables substantially compensation of compressive stress in the core by residual tensile strain in the cladding, thereby reducing to very low values birefringence induced optical signal shift between TE and TM modes of propagation of an optical signal.
摘要:
Several methods are used in novel ways with newly identified and viable parameters to decrease the peak transition energies of the pseudomorphic InGaAs/GaAs heterostructures. These techniques, taken separately or in combination, suffice to permit operation of light emitting devices at wavelengths of 1.3 &mgr;m or greater of light-emitting electro-optic devices. These methods or techniques, by example, include: (1) utilizing new superlattice structures having high In concentrations in the active region, (2) utilizing strain compensation to increase the usable layer thickness for quantum wells with appropriately high In concentrations, (3) utilizing appropriately small amounts of nitrogen (N) in the pseudomorphic InGaAsN/GaAs laser structure, and (4) use of nominal (111) oriented substrates to increase the usable layer thickness for quantum wells with appropriately high In concentrations. In all of the above techniques, gain offset may be utilized in VCSELs to detune the emission energy lower than the peak transition energy, by about 25 meV or even more, via appropriate DBR spacing. Gain offset may also be utilized in some forms of in-plane lasers. Increased temperature may also be used to decrease peak transition energy (and therefore the emission energy) by about 50 meV/100° C. All these techniques are furthermore applicable to other material systems, for example, extending the emission wavelength for laser diodes grown on InP substrates. Additionally, structures which utilize the above techniques are discussed.
摘要:
The specification describes an improved form of heterostructure laser, termed a "Rib-Loc" laser. It is an easily fabricated device with desirable electrical and optical properties. The Rib-Loc is simple to fabricate because a single, self-aligned rib provides ohmic contact, current confinement and lateral waveguiding. A deeply etched P-cladding layer outside the rib provides the positive index change needed for an index-guided laser. The large optical cavity increases the maximum power output and reduces the aspect ratio of the beam.
摘要:
A light emitting diode designed to emit primarily at 1.3 microns comprises a crystal having a plurality of lattice matched layers including an n-type indium phosphide front surface layer, an n-type indium phosphide buffer layer, a p-type indium gallium arsenide phosphide active layer, a p-type indium phosphide confining layer and an indium gallium arsenide back surface layer, and an annular front contact and a limited area back contact to the crystal.
摘要:
Fine featured devices are produced by a series of fabrication steps including exposing selective surface regions to irradiation, e.g. to an ion beam, generally to result in removal of masking material within irradiated regions. In most instances, subsequent etching is under conditions such that bared material is preferentially removed. Etch-removal and irradiation are such that overgrown material is of device quality at least in etched regions. The inventive process is of particular value in the fabrication of integrated circuits, e.g. circuits performing electronic and/or optical functions. The inventive process is expediently used in the fabrication of structures having minimum feature size of 1 micrometer and smaller. Patterning is dependent upon masking material of a maximum thickness of 100 .ANG..