Abstract: Intersecting quantum wells form a T-shaped structure. Quantum bound states exist due to the spreading out of the wave function in the T-junction region. The confined state leads to formation of a quantum wire in which one-dimensional carrier behavior extends along a wire-like region defined by the intersecting planes of the two wells. By embedding such a region in a T-shaped optical waveguide, a quantum wire laser characterized by low-threshold stimulated emission in the one-dimensional quantum limit is provided.

Abstract: The present invention is a method for making field effect devices, such as a field effect transistors, having ultrashort gate lengths so low as five hundred angstroms or less. In accordance with the invention the gate structure is grown vertically on a substrate by thin film deposition so that the length dimension of the gate is perpendicular to a major surface of the substrate. An edge of the gate-containing substrate is exposed, and the structure comprising the source, drain and channel is grown on the edge. Using this approach, field effect devices with precisely controlled gate lengths of less than 100 angstroms are achievable. Moreover the active regions of the device can be immersed within semiconductor material so that surface properties do not deteriorate device performance.

Abstract: The present invention is a method for making field effect devices, such as a field effect transistors, having ultrashort gate lengths so low as five hundred angstroms or less. In accordance with the invention the gate structure is grown vertically on a substrate by thin film deposition so that the length dimension of the gate is perpendicular to a major surface of the substrate. An edge of the gate-containing substrate is exposed, and the structure comprising the source, drain and channel is grown on the edge. Using this approach, field effect devices with precisely controlled gate lengths of less than 100 angstroms are achievable. Moreover the active regions of the device can be immersed within semiconductor material so that surface properties do not deteriorate device performance.

Abstract: The disclosed novel solid state electronic devices comprise a two-dimensional electron gas (2DEG), emission means of ballistic 2DEG electrons, collection means of 2DEG electrons, and control means disposed between the emissions means and the collection means such that ballistic 2DEG electrons that travel from the emission means to the collections means pass through a portion of the device that underlies the control means. By means of the control means the electron density in the portion of the device can be changed, whereby the path of ballistic 2DEG electrons can be affected, in a manner analogous to refraction in optics. This "electron refraction" makes possible a variety of devices, e.g., switches and logic elements.

Abstract: An acoustic superlattice of alternating layers of different acoustic impedance is disclosed as a filter for high frequency phonons. Applications discussed include spectrometers, acoustic imaging apparatus, and cavity resonators.

Abstract: The mobility of a relatively narrow bandgap semiconductor material can be significantly enhanced by incorporating it into a multilayered structure (10) comprising a first plurality of relatively narrow bandgap layers (12) of the material and a second plurality of wider bandgap semiconductor layers (14) interleaved with and contiguous with the first plurality. The wide bandgap and narrow bandgap layers are substantially lattice-matched to one another, and the wide bandgap layers are doped such that the impurity concentration-thickness product therein is greater than the same product in the narrow bandgap layers. The fabrication of the structure by MBE to enhance the mobility of GaAs is specifically described. In this case, the narrow bandgap layers (12) comprise GaAs and are unintentionally doped to about 10.sup.14 /cm.sup.3, whereas the wide bandgap layers (14) comprise AlGaAs doped n-type to about 10.sup.16 to 10.sup.18 /cm.sup.3. The incorporation of this structure in an FET is also described.

Abstract: The mobility of a relatively narrow bandgap semiconductor material can be significantly enhanced by incorporating it into a multilayered structure (10) comprising a first plurality of relatively narrow bandgap layers (12) of the material and a second plurality of wider bandgap semiconductor layers (14) interleaved with and contiguous with the first plurality. The wide bandgap and narrow bandgap layers are substantially lattice-matched to one another, and the wide bandgap layers are doped such that the impurity concentration-thickness product therein is greater than the same product in the narrow bandgap layers. The fabrication of the structure by MBE to enhance the mobility of GaAs is specifically described. In this case, the narrow bandgap layers (12) comprise GaAs and are unintentionally doped to about 10.sup.14 /cm.sup.3, whereas the wide bandgap layers (14) comprise AlGaAs doped n-type to about 10.sup.16 to 10.sup.18 /cm.sup.3. The incorporation of this structure in an FET is also described.

Abstract: The mobility of a relatively narrow bandgap semiconductor material can be significantly enhanced by incorporating it into a multilayered structure (10) comprising a first plurality of relatively narrow bandgap layers (12) of the material and a second plurality of wider bandgap semiconductor layers (14) interleaved with and contiguous with the first plurality. The wide bandgap and narrow bandgap layers are substantially lattice-matched to one another, and the wide bandgap layers are doped such that the impurity concentration-thickness product therein is greater than the same product in the narrow bandgap layers. The fabrication of the structure by MBE to enhance the mobility of GaAs is specifically described. In this case, the narrow bandgap layers (12) comprise GaAs and are unintentionally doped to about 10.sup.14 /cm.sup.3, whereas the wide bandgap layers (14) comprise AlGaAs doped n-type to about 10.sup.16 to 10.sup.18 /cm.sup.3. The incorporation of this structure in an FET is also described.