Abstract: The incorporation of a GaAs layer that is intentionally p-doped into a standard HEMT device structure has been shown to produce a HEMT transistor with greatly enhanced radiation hardness under exposure to neutron radiation.

Abstract: A semiconductor device, specifically an FET, having a body which includes a matrix of semiconductor material, specifically silicon, having an array of individual rods of conductive material, specifically TaSi.sub.2, disposed therein. The rods form Schottky barriers with the semiconductor material. A gate contact is made to several of the rods at one end, and source and drain contacts are made to the matrix of semicondcutor material. Current flow in the semiconductor material of the matrix between the source and the drain is controlled by applying biasing potential to the gate contact to enlarge the depletion zones around the rods.

Abstract: A multi-wavelength optical demultiplexer includes at least three relatively thick layers of direct band gap semiconductor material deposited on a substrate. The various thick layers are separated by respective, individual, relatively thin layers of lattice matched material having a larger band gap than the materials in the thick layers. The thin layers, deposited on the thick layers, serve as a potential barrier to prevent photo-electrons generated in one layer from entering another. Ohmic contacts of donor impurity diffusion are provided at opposite ends of each relatively thick layer. With a substrate of gallium arsenide, the relatively thick layers can be aluminum gallium arsenide of varying compositions, in which the proportions of aluminum to gallium decreases from the layer distal to the substrate to the layer proximal to the substrate.