Abstract: Resonant tunneling devices having improved peak-to-valley current ratios are disclosed. The resonant tunneling device comprises a quantum well layer surrounded by first and second barrier layers, the first and second barrier layers being comprised of an indirect first III-V compound semiconductor. The first barrier layer being formed on a substrate of a second III-V compound semiconductor having a lattice constant larger than the lattice constant of the first barrier layer thereby inducing a biaxial stress in the first barrier layer. The biaxial stress results in an energy shift at resonance that increases the peak to valley current ratio of the device.

Abstract: A long wavelength detector is formed by coupling a highly doped cathode to an anode through an undoped quantum well or superlattice filter structure. The absorption mechanism is free-carrier absorption in a heavily doped direct bandgap semiconductor (the cathode). The cathode material is preferably chosen such that the conduction band edge is lower than the conduction band edge of the material forming the well of the resonant-tunneling filter. The cathode material should also be semiconductor material of relatively narrow direct bandgap with low effective electron mass. The detector device is biased so that electrons pass through the filter structure by resonant tunneling. To stimulate conduction, incident radiation must have a frequency (i.e., photon energy) sufficient to boost the energy of the cathode electrons from the Fermi energy level of the cathode to the resonance energy level of the quantum-well filter.

Abstract: Quantum mechanical effect devices incorporate means for interrupting the two-dimensional carrier gas of a modulation doped structure to produce periodic potential variations which provide superlattice-like effects on current flowing nearby. The modulation doped structures incorporate specialized structures displaced from a current path which simultaneously confine the two-dimensional carrier gas into a quasi-one-dimensional carrier gas and subject the thus confined carrier gas and current flowing therein to superlattice-like effects by inducing periodic potential variations along the current path. The induced variations are produced by etching corrugations in the device edges or by forming them in biasing gates.

Abstract: A multilayer semiconductor structure is disclosed having a plurality of conducting layers separated by a barrier layer. A common contact extends from an upper exposed surface to all the layers of the device and a surface contact extends from the upper surface into an uppermost conducting layer. Each of the conducting layers defines an independent channel of current flow thereby providing at least two independent current paths between the common contact and the surface contact. A Schottky barrier electrode is disposed on the surface of the structure between the common and surface contacts and is operable to selectively deplete charge carriers within the conducting layers sequentially to cause current to flow through the desired channel. The current flow in each channel results in an independent I/V characteristic curve in which one channel is linear and the other channel is non-linear.

Abstract: A multilayer contact is shown in a heterojunction device. One contact extends through two or more vertical, conducting layers. Two contacts deposited on a common surface. Each contact separately bias different layers beneath the surface. A Schottky barrier between the contacts establishes a depletion region that electrically controls the current flow path between the contacts.

Abstract: A single or multilayer optical interference filter and method of forming filter by ion implantation. One or more layers of nitrogen ions are implanted into a single crystal silicon with the crystal at a temperature of from about 600.degree. C. to about 1000.degree. C. The implanted ions create a buried layer(s) of silicon nitride (Si.sub.3 N.sub.4) whose refractive index is substantially different from that of silicon (Si) such that appreciable multiple reflection of incident light occurs between the buried layer(s) and the front surface. The resulting interference maxima and minima in transmitted or reflected light which occur at well-defined positions in wavelength may be controlled both in amplitude and wavelength position. The ions may be implanted in layers at different depths to produce a "thin film" interference filter.