Abstract: A monolithically integrated, optoelectronic VLSI circuit is fabricated by growing optical devices on the compound semiconductor surface of a VLSI chip or wafer having pre-existing electronic devices formed thereon. In accordance with an illustrative embodiment of the present invention, a large array of surface normal optical modulating devices such as multiple quantum well modulators is grown on an impurity free surface of a VLSI chip having an array of FETs already provided thereon. The growth of such devices takes place at temperatures below 430.degree. C. on a compound semiconductor surface which has a highly ordered atomic structure. An optoelectronic switch constructed in this manner is capable of addressing electronic chips in systems handling 10,000 or more input/output optical beams.

Abstract: A method and apparatus for modulating an optical signal, and a method for fabricating such an apparatus. The modulator comprises a membrane having at least one layer, and a substrate, spaced to form a air gap. The membrane is suspended in a first position over the substrate by a flexible support arrangement such that the size of the air gap may vary. The layers of the membrane are formed so that the refractive indices of such layers have a particular relationship to the refractive index of the substrate, and have a particular thickness. Bias is applied to the membrane and the substrate to create a force that causes the membrane to change its position relative to the substrate, causing the size of the air gap to change. The reflectivity of the device to an optical signal varies as the size of the air gap changes.

Abstract: An integrated semiconductor device is formed by bonding the conductors of one fabricated semiconductor device having a substrate to the conductors on another fabricated semiconductor device having a substrate, flowing an etch-resist in the form of an uncured cement (e.g. epoxy) between the devices, allowing the etch-resist to solidify, and removing the substrate from one of the semiconductor devices. Preferably the etch-resist epoxy is retained to impart mechanical strength to the device. More specifically, a hybrid semiconductor device is formed by bonding the conductors of one or more GaAs/AlGaAs multiple quantum well modulators to conductors on an IC chip, wicking an uncured epoxy between the modulators and the chip, allowing the epoxy to cure, and removing the substrate from the modulator.

Abstract: A semiconductor device is provided that includes an optical cavity that is designed to provide a prescribed resonant optical wavelength. The optical cavity includes a mirror structure deposited on top of a substrate and a multi-layer region such as an electroabsorptive region, for example, deposited over the mirror structure. A partial antireflective coating is deposited over the multi-layer region. The mirror structure and the multilayer region have a thickness variation sufficient to yield a resonant optical wavelength that deviates from the prescribed resonant wavelength. The partial antireflective coating has a non-uniform thickness variation that causes the resonant optical wavelength to shift substantially toward the prescribed resonant optical wavelength.

Abstract: A multi-layer mirror structure included in a surface-normal semiconductor optical cavity is fabricated in a deposition reactor dedicated to that purpose alone. Additional layers of the device are subsequently deposited on top of the mirror structure in a second reactor. In practice, the dedicated reactor produces layers whose thickness variations over their entire extents are considerably less than the thickness variations of layers made in the second reactor. This coupled with the fact that the actual achieved thickness of the mirror structure can be conveniently measured before commencing deposition of a prescribed thickness of the additional layers makes it possible to fabricate a specified-thickness optical cavity within tight tolerances in a high-yield manner.

Abstract: A method for desorbing the surface oxide on a silicon substrate is performed by implanting particles such at atomic or ionic hydrogen into the oxide layer on the silicon substrate. The oxide is then removed by breaking the bonds between the silicon and oxygen atoms within the oxide. The bonds may be broken by heating the substrate, for example. The temperature to which the substrate must be raised is substantially less than the temperature required to desorb an oxide layer that has not undergone an implantation step. In one particular example, the particles implanted into the oxide surface are hydrogen ions generated by electron cyclotron resonance.

Abstract: A method and apparatus for modulating an optical signal using a micromechanical modulator are disclosed. The modulator comprises a membrane, which consists of at least one layer, and a substrate, spaced to form an air gap. The layers of the membrane are characterized in that there is a relationship between the refractive indices of the layers and the refractive index of the substrate. The membrane is suspended in a first position over the substrate by a flexible support arrangement. Bias is applied to the membrane and the substrate to create an electrostatic force to move the membrane towards the substrate to a second position. The reflectivity of the device to an optical signal changes as the membrane moves from the first position to the second position, thereby modulating the signal.

Abstract: An in-situ method is disclosed for highly accurate lattice matching using reflection high energy electron diffraction dynamics. The method includes the steps of providing a substrate of a first semiconductor material and initiating growth of a second semiconductor material thereon. The oscillation amplitude of intensity I of waveform cycles is monitored using reflection high energy electron diffraction. A maximum intensity I.sup.+ and a minimum intensity I.sup.- is determined over a predetermined number of waveform cycles. The intensity drop .DELTA.I from initial reflectivity to minimum reflectivity of the waveform cycles is determined and a normalized figure of merit FM is calculated for the predetermined number of waveform cycles using the relationship: ##EQU1## The fluxes of the second semiconductor material are then adjusted to maximize FM and optimize lattice matching.

Abstract: A technique is described for the preparation of a thin film of a silicon nitride diffusion barrier to gallium on a silicon integrated circuit chip. The technique involves reacting nitrogen and silane in a ratio of 53:1 to 300:1 in a plasma enhanced chemical vapor deposition apparatus. The described technique is of interest for use in the monolithic integration of interconnected GaAs/AlGaAs double heterostructures, modulators and silicon MOSFET structures.

Abstract: A semiconductor device is provided that includes an optical cavity that is designed to provide a prescribed resonant optical wavelength. The optical cavity includes a mirror structure deposited on top of a substrate and a multi-layer region such as an electroabsorptive region, for example, deposited over the mirror structure. A partial antireflective coating is deposited over the multi-layer region. The mirror structure and the multilayer region have a thickness variation sufficient to yield a resonant optical wavelength that deviates from the prescribed resonant wavelength. The partial antireflective coating has a non-uniform thickness variation that causes the resonant optical wavelength to shift substantially toward the prescribed resonant optical wavelength.

Abstract: Nonpolar substrates comprising off-axis growth regions for the growth of polar semiconductors, and a method for making such substrates, are disclosed. According to the invention, an erodible material, such as a photoresist, is applied to a substrate at a site and is exposed to radiation at that site which has an linear variation in energy at the surface of the erodible material. Due to this variation in exposure energy, a taper results in the erodible material after development. The tapered region is then etched in a manner which etches both the erodible layer and the underlying substrate. The taper in the erodible layer provides a varying attenuation during the etching process such that the taper of the erodible layer is transferred to the substrate.

Abstract: An integrated semiconductor device is formed by bonding the conductors of one fabricated semiconductor device having a substrate to the conductors on another fabricated semiconductor device having a substrate, flowing an etch-resist in the form of a photoresist between the devices, allowing the etch-resist to dry, and removing the substrate from one of the semiconductor devices. Preferably the etch-resist is retained to impart mechanical strength to the device. More specifically, a hybrid semiconductor device is formed by bonding the conductors of one or more GaAs/AlGaAs multiple quantum well modulators to conductors on an IC chip, flowing a photoresist between the modulators and the chip, allowing the photoresist to dry, and removing the substrate from the modulator.

Abstract: A tunable monolithic integrated photodetector (10) detects a selected wavelength of incident light within a wavelength range. The photodetector comprises a multiple quantum well (MQW) filter means for receiving and filtering the incident light, and an MQW detector means for receiving light from the MQW filter means and for detecting the selected wavelength. A fixed voltage bias V.sub..DELTA. is disposed between the filter means and the detector means for causing the filter means to absorb light wavelengths around the selected wavelength to thereby enhance the detectability of the selected wavelength. Further, a variable voltage bias V.sub.P is selectively and proportionally imposed on both the filter means and the detector means for permitting tuning of the photodetector. A fixed filter may also be employed for filtering the incident light so that light wavelengths which are outside the range of the photodetector are eliminated.

Abstract: Carriers are permitted escape from quantum wells within a semiconductor device in the minimum amount of time by utilizing semiconductor material in the barrier layers around the quantum well wherein the barrier layers exhibit an effective bandgap energy less than the sum of the longitudinal optical phonon energy and the exciton absorption energy.

Abstract: This invention is an optical connective device which can have a two-dimensional array of optical fibers. The device can be comprised of a single piece of light conducting material such as glass, plastic or the like shaped to have a slab support member having pillars which project outward from opposing surfaces. The pillars on one of the opposing surfaces are optically aligned with corresponding pillars on the other opposing surface. The length of a pillar can be as small as its diameter. The ends of the pillars can be flat or curved to form a lens and each pillar can be accurately located to an arbitary position. The optical connective device can be sandwiched between chips to provide an integrated circuit chip-to-chip connective device for a stack of two or more chips.

Abstract: In a semiconductor optical modulator, two semiconductor materials having different refractive indices are grown in an alternating sequence of layers to form a semiconductor mirror wherein each layer has approximately a quarter wave thickness for a predetermined wavelength. Delta doping is performed at each heterointerface. The delta doping conductivity type alternates from one heterointerface to the next. Lateral surface contacts are selectively made to the n-type heterointerfaces on one edge of the mirror and to the p-type heterointerfaces on the other edge of the mirror. An interleaved ohmic contact structure results within the modulator. By applying a nominally low voltage to the lateral surface contacts, it is possible to effect refractive index changes in the layers so that the mirror performs reflection or transmission of an impinging light beam.

Abstract: This invention concerns with a non-alloyed ohmic contact to III-V semiconductor material in a III-V semiconductor device on a Si base. The ohmic contact includes at least one set of layers comprising a delta-doped monolayer and a thin layer of undoped III-V semiconductor material which is 2.5 nm or less in thickness, said at least one set of layers being upon a doped III-V semiconductor layer. An epitaxial layer of metal upon an uppermost of the layers of the said set of layers completes the ohmic contact, said metal being capable of wetting the surface of the III-V semiconductor material and of being epitaxially grown on the said III-V semiconductor material. At least the said at least one set of layers and the metal layer are deposited by Molecular Beam Epitaxy, thus avoiding formation of oxides and growing the metal epitaxially so that the metal layer is crystalline at least near the interface between the metal and the semiconductor material.

Abstract: Lower switching energies, enhanced electroabsorption and reduced tolerances on the operating wavelength of incident light are achieved while contrast between low and high absorption states is maintained in accordance with the principles of the invention by a self electrooptic device including an intrinsic quantum well region having an asymmetric electronic characteristic across a narrow bandgap subregion between the two wide bandgap layers defining the quantum well region. As a result, the quantum well region polarizes electrons and holes within the subregion in an opposite direction relative to a direction for an electric field applied to the device. The asymmetric electronic characteristic is realized as a compositionally graded, narrow bandgap layer or as a pair of coupled narrow bandgap layers of differing thicknesses separated by a thin wide bandgap layer.