Abstract: An apparatus for and a method of making heterojunction source-drain insulated gate field-effect transistors in order to obtain higher gain-bandwidth products at microwave frequencies. A semi-insulating InP semiconductor substrate is provided with a ternary alloy layer of p-type Ga.sub.0.47 In.sub.0.53 As, or optionally, an acceptor-doped p-type bulk of Ga.sub.0.47 In.sub.0.53 As can be substituted. Troughs are shaped in the substrate and layer for receiving a material lattice-matched to the n.sup.+ p-type Ga.sub.0.47 In.sub.0.53 As to perform as the source and drain contacts, n.sup.+ doped InP might be a suitable material. An optional method for forming the contacts calls for directing a stream of phosphine and hydrogen onto source and drain contact windows contacting the Ga.sub.0.47 In.sub.0.53 As which is heated to 750.degree. C. for about 15 minutes. This creates graded heterojunction source and drain contacts having a lattice-matching variable composition.

Abstract: An improved apparatus modulates greater currents at higher frequencies over extended bandwidths. In addition to conventional biasing and modulation a beam of electrons is directed onto a heterojunction-diode device disposed to receive the modulating electron beam. The heterojunction diode device is fabricated from two different semiconducting materials having identical crystalline lattice structures, different fundamental energy bandgaps and different impurity types of different concentrations. This combination of properties assures greater output currents, higher frequency modulation and increased bandwidths.

Abstract: A metal semiconductor field effect transistor (MESFET) has a Schottky barrier gate formed by depositing an electron transparent electrode to allow its modulation by electric fields and electron beams. The electrode is coupled to an electric field source which is maintained constant or is varied for changing the current flow between the source electrode and drain electrode. An impinging modulating electron beam is directed through the transparent gate to further modulate the current flow between the source electrode and drain electrode and to effect an overall gain in the neighborhood of 10.sup.6. The accelerating potential of the electron beams is of at least an order of magnitude less than conventional cathode ray tube potentials to reduce the possibility of damage to the MESFET material and, since a number of the MESFETS can be modulated by one or more electron beams, they have wide frequency selectivities, broad bandwidths and high switching time capabilities.

Abstract: A method for depositing high quality indium phosphide layers heteroepitaxly on GaAs substrates by controlling the growth between them of an interfacial quaternary alloy of In.sub.y Ga.sub.1-y As.sub.x P.sub.1-x.

Abstract: A method and means of monitoring the quality of a fluid dielectric capacitor by measuring the Kerr signal of a dielectric fluid which has the desired dielectric and breakdown properties and continually measuring the Kerr signal of the same fluid dielectric while in use to determine if there is any degradation of the fluid in use. The means for measuring the Kerr signal is by projecting a high intensity light beam such as from a laser source through the dielectric fluid of a capacitor between two of the plates and detecting the amount of light passed through the dielectric which is an indication of the condition of the dielectric liquid.

Abstract: A light emitting diode with emission wavelength in the 1.06.mu.m region suitable for use with the 1.06.mu.m transmission window in optical fibers. The diode is fabricated by liquid phase epitaxial growth of p and n type InAs.sub.x P.sub.1-x layers on InP substrates.