Abstract: In the liquid phase epitaxy growth of Group III-V compound semiconductors using boat-slider apparatus, melt-carry-over is essentially eliminated by prebaking the metallic solvent (e.g., In shot) in the boat to form ingots and then etching the ingots in dilute nitric or hydrochloric acid prior to adding solutes (e.g., GaAs, InP, dopants). This process removes contaminants which coalesce on the ingots and cause poor wipe-off.

Abstract: In a CRT display device the target comprises a multilayered semiconductor including a p-n junction and at least one current-blocking layer. The e-beam is locally absorbed in the current-blocking layer so as to open a narrow zone which allows charge to flow through the forward biased p-n junction. The injection current produces a local spot of light which radiates from the opposite side of the device and whose position is varied by scanning the e-beam. In one embodiment the current-blocking layer is a semi-insulating semiconductor layer, and in another embodiment the current-blocking layer comprises the base of a normally cut-off transistor.

Abstract: In.sub.0.53 Ga.sub.0.47 As p-i-n photodiodes with room temperature dark currents as low as 0.1 nA at -10 V bias are realized by introducing a wide bandgap (e.g., quaternary InGaAsP) cap layer on the ternary InGaAs.

Abstract: Thermal degradation of compound single crystal substrates (e.g., InP) containing a relatively volatile element (e.g., P) prior to LPE growth has been virtually eliminated by an improved protection technique. A partial pressure of the volatile element is provided by a solution (e.g., Sn-In-P) localized inside a chamber which is external to the LPE boat and which surrounds substrate prior to growth, thereby preventing thermal damage to the substrate surface. Applicability of the technique to other epitaxial growth processes (e.g., VPE and MBE) is also discussed.

Abstract: The property of materials in the GaAs/AlGaAs system, whereby at certain doses proton bombarded n-type material becomes highly resistive but p-type material remains highly conductive, is utilized to fabrication of integrated circuits which include buried semiconductor interconnections or bus bars between devices.

Abstract: The property of materials in the InP system, whereby helium ion or deuteron bombarded p-type material becomes highly resistive but n-type material remains relatively conductive, is utilized to fabricate integrated circuits which include buried semiconductor interconnections or bus bars between devices.

Abstract: V-grooves are etched in Group III-V compound semiconductors using a composite mask comprising a thin native oxide layer on the semiconductor and a dielectric etch mask on the native oxide. Described in detail is the application of this technique to etching V-grooves in InP for the fabrication of CSBH InP/InGaAsP lasers.

Abstract: Oxide (R.sub.m O.sub.n) films are grown by evaporation from separate sources of element (R) and an oxide (M.sub.r O.sub.s) which serves as the oxygen source. The oxide (M.sub.r O.sub.s) should sublimate congruently; i.e., without decomposing into oxygen and its constituent element (M). On the growth surface this oxide (M.sub.r O.sub.s) can react with the element (R) to form another oxide (R.sub.m O.sub.n) that is thermodynamically more stable:mR+M.sub.r O.sub.s .fwdarw.R.sub.m O.sub.n +M.sub.r O.sub.s-nUsing this technique, films of Al.sub.2 O.sub.3, MgO, SiO.sub.2, and MgAl.sub.2 O.sub.4 have been grown using As.sub.2 O.sub.3 or Sb.sub.2 O.sub.3 as the oxygen source.

Abstract: Described is a high gain, soft X-ray pumped, inner-shell, photoionization amplifier/laser in Cd or Zn vapors. The soft X-ray photoionization, generated by a laser-produced plasma or other high intensity X-ray source, preferentially removes inner-shell d-electrons from neutral atoms leaving them ionized in a .sup.2 D state and producing a population inversion with respect to a lower lying .sup.2 p state. Also described are techniques for achieving inversions with respect to the ion ground state of Cd, Zn or Hg by optically pumping from the inner-shell ionized state to a higher energy level. Iso-electronic scaling of Cd, Zn and Hg suggests similar lasing phenomena exist, for example, in Ga, In and Tl ions, respectively, and also higher iso-electronic sequences.

Abstract: A movable part of a robot, such as the fingers of the robot hand, are provided with an array of tactile elements mounted on a substrate. Each element includes a magnetic dipole embedded in a compliant medium on one side of the substrate and a magnetic sensor on the other side of the substrate. The dipole and sensor are in parallel planes. A force or torque deforms the compliant medium and displaces the magnetic dipoles with respect to the sensor. The sensor detects the change in magnetic field and produces an electrical signal which is used to control the robot. Magnetoresistive sensors are preferred. To detect torque, each element illustratively includes four sensors arranged at 90.degree. to one another and a magnetic dipole oriented at 45.degree. to each sensor.

Abstract: A single-wavelength, bidirectional fiber optic transmission system is described in which at each terminal the output radiation of a light source (LED or semiconductor laser) is coupled through a small diameter hole in the active area of a photodiode into the core of a larger diameter transmission fiber. On the other hand, radiation propagating through the fiber in the opposite direction exits from the fiber with a large NA so that most of it is incident on the active area of the photodiode and little is lost through the hole. Also described are a number of photodiode configurations for use in such a system, as well as dual photodiodes to perform both signal detection and output monitoring functions.

Abstract: Selected portions of the interior surface of a substrate tube, or of the cladding or core layers deposited on the interior surface of the substrate tube, are treated by one or more process steps such as shaping, diffusing, leaching, or depositing. Patterning processes such as photolithography and lift-off are employed to define the selected portions. The resulting core and/or cladding layers of the fiber can be made to have a variety of geometric shapes and composition profiles useful, for example, in realizing birefringent fibers and multiple-core fibers. Also described is the similar treating of metal layers and the incorporation of such layers into the fiber.

Abstract: Prior to packaging, semiconductor lasers are purged by being subjected first to high temperature and high current simultaneously so as to suppress stimulated emission and stress the shunt paths which allow leakage current to flow around the active region. A prudent, but nonessential, second step is to lower the temperature and/or current so that the lasers emit stimulated emission (preferably strongly, near the peak output power), thereby stressing the active region. Lasers subjected to such a purge exhibit stabilized degradation rates in short times (of the order of a few hours) and provide a robust population which meets the performance criteria of long lifetime systems.

Abstract: A nonintegrating, high sensitivity, wide dynamic range receiver is described. A voltage dependent current source is connected in negative feedback with a forward voltage amplifier. The transconductance of the current source is essentially independent of frequency within the signal bandwidth frequency, and the feedback pole is the dominant pole in the loop gain. To prevent saturation by high intensity input signals the receiver is combined with a range extender circuit.

Abstract: In the liquid phase epitaxy growth of Group III-V compound semiconductors using boat-slider apparatus, melt-carry-over is essentially eliminated by prebaking the metallic solvent (e.g., In shot) in the boat to form ingots and then etching the ingots in dilute nitric or hydrochloric acid prior to adding solutes (e.g., GaAs, InP, dopants). This process removes contaminants which coalesce on the ingots and cause poor wipe-off.

Abstract: In the fabrication of buried heterostructure InP/InGaAsP lasers, mask undercutting during the mesa etching step is alleviated by a combination of steps which includes the epitaxial growth of a large bandgap InGaAsP cap layer (1.05 eV.ltorsim.E.sub.g .ltorsim.1.24 eV) and the plasma deposition of a SiO.sub.2 etch masking layer. Alternatively, the cap layer may be a bilayer: an InGaAs layer or narrow bandgap InGaAsP (E.sub.g .ltorsim.1.05 eV), which has low contact resistance, and a thin InP protective layer which reduces undercutting and which is removed after LPE regrowth is complete. In both cases, etching at a low temperature with agitation has been found advantageous.

Abstract: Described is a robot having a proximity sensor which is based on the reentrant-loop magnetic effect. In one embodiment this sensor in a robot hand can detect the position and orientation of magnetized objects within about a 5 cm range, independently of the speed of approach.

Abstract: A nonintegrating, high sensitivity, wide dynamic range receiver is described. A voltage dependent current source is connected in negative feedback with a forward voltage amplifier. The transconductance of the current source is essentially independent of frequency within the signal bandwidth frequency, and the feedback pole is the dominant pole in the loop gain. To prevent saturation by high intensity input signals the receiver is combined with a range extender circuit.

Abstract: The property of Group III-V compound materials, whereby ion bombarded material becomes highly resistive but recovers its original low resistivity by annealing at a temperature which is dopant and material dependant, is utilized to fabricate integrated circuits which include buried semiconductor interconnections or bus bars between devices.

Abstract: Two opposing fingers of a robot hand are each provided with an array of optical devices which are capable of being in optical communication with one another through the gap between the fingers. One finger is provided with an array of light emitters and the other is provided with an array of light recepetors. By taking advantage of the motion of the robot hand and the small size of the optical devices, the shape of an object between the fingers can be detected by using at least one linear set, and preferably at least two linear sets, of devices in each array. Illustratively, the linear sets form a T-shaped array or a U-shaped array and are disposed along the edges of the fingers. In one embodiment the emitters are GRIN rod lenses coupled through a fiber cable to a light source, and the receptors are also GRIN rod lenses coupled through a fiber cable to a camera system. A manufacturing method utilizing such a sensor to identify the shape of objects is also described.