International Business Machines Corporation

Volker Graf

Carl A Mueller

Peter Vettiger

Peter Roentgen

Peter L Buchmann

Peter D Hoh

Pierre L Gueret

Wilhelm Heuberger

Theodor O Mohr

Yvan Galeuchet

A method for making layered structures of artificial high T.sub.c superconductor compounds by which on top of a seed crystal having a lattice structure matching the lattice structure of the superconductor compound to be made, oxide layers of all constituent components are epitaxially grown in a predetermined sequence so as to create a sandwich structure not found in natural crystals. The epitaxial deposition of the constituent components is performed in a reaction chamber having evaporation facilities, inlets for metal-organic gases, and inlets for background gases including oxygen.

Method of making artificial layered high T.sub.c superconductors

A method, and devices produced therewith, for the epitaxial growth of sub-micron semiconductor structures with at least one crystal plane-dependently grown, buried active layer (24) consisting of a III-V compound. The active layer (24) and adjacent embedding layers (23, 25) form a heterostructure produced in a one-step growth process not requiring removal of the sample from the growth chamber in between layer depositions. The layers of the structure are grown on a semiconductor substrate (21) having a structured surface exposing regions of different crystal orientation providing growth and no-growth-planes for the selective growth process. The method allows the production of multiple, closely spaced active layers and of layers consisting of adjoining sections having different physical properties.

Method for the epitaxial growth of a semiconductor structure

Process for producing temperature-stable undercut profiles for use in semiconductor fabrication. The process is based on the phenomenon of high etch-rate selectivity between RF- and LF- PECVD-grown silicon nitride films (12G and 13G, respectively) that are deposited on top of each other. By choosing proper film and process parameters, these PECVD nitride structures can be made stress-free: the tensile stress of the RF film (12G) compensates the compressive stress of the LF film (13G). Also disclosed is an application of a T-shaped structure (15), produced with the new process, in a method for fabricating fully self-aligned 'dummy' gate sub-micron MESFETs.

Process for producing undercut dummy gate mask profiles for MESFETs

The transistor comprises two electrodes, source (12) and drain (13), with a semiconductor tunnel channel (11) arranged therebetween. A gate (14) for applying control signals is coupled to the channel. The semiconductor, at low temperatures, behaves like an insulator with a low barrier (some meV) through which charge carriers can tunnel under the influence of an applied drain voltage. The tunnel current can be controlled by a gate voltage V.sub.G which modifies the barrier height between source and drain thereby changing the tunnel probability.

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Wollerau, Switzerland

Volker Graf