Abstract: FETs and quantum well diodes are combined on the same semi-insulating substrate, while providing the FETs with protection from spurious voltages. A deeply buried P region in the semi-insulating substrate is partitioned by a high resistivity proton implanted region, to provide both the P region of the quantum well diode and an isolating buried P layer for the FETs.

Abstract: A semiconductor device is disclosed, which includes a multiple negative differential resistance element having negative differential resistance characteristics at at least two places in the current-voltage characteristics, and which is suitable for constructing a neural network having a high density integration and a high reliability.

Abstract: A novel light emitting semiconductor device is disclosed. The device utilizes real space transfer (RST) of carriers, and comprises regions of opposite conductivity type separated by a barrier layer. The first region (termed the "emitter") comprises at least two contacts. Application of appropriate bias between the two contacts and between the emitter and the second region results in injection of hot carriers into the second region, resulting in luminescence in the second region. The invention can be embodied in coherent as well as incoherent light sources. A preferred embodiment is a vertical cavity surface emitting laser. The device can serve as a novel logic element that has electrical inputs and an optical output, and provides a non-trivial logic function.

Abstract: A field effect type photo-detector comprises a semiconductor buffer layer arranged on a substrate. A semiconductor activation layer is arranged on that buffer layer, and a source electrode, a drain electrode and a gate electrode are arranged on the activation layer. A depletion layer for controlling a current flow between the source electrode and the drain electrode is created in the activation layer by applying a voltage to the gate electrode. When light irradiates the activation layer, the depletion layer changes. The buffer layer has a wider band gap than that of the activation layer and has an energy gap which serves as a barrier to carriers. The buffer layer has a sufficiently wide band gap to prevent the absorption of light having an equal wavelength to that of the light irradiated to the activation layer.