Abstract: A mesa release and deposition (MRD) method realizes stress relief in GaAs layers on Si, useful in practical device applications. A thin AlAs layer is incorporated in the heteroepitaxial GaAs layer about l.mu.m from the GaAs/Si interface. Mesas are etched down to the AlAs release layer and subsequently underetched in a 5% HF-solution at room temperature. Photoresist clamps keep the mesas in their exact position during the underetch process which results in a self-aligned re-deposition on the substrate after resist removal. Spatially resolved photoluminescence on GaAs on Si mesas before and after the MRD process was used to demonstrate the stress relief. GaAs epitaxy layers are thereafter grown on the GaAs on Si mesas. Spatially resolved photoluminescence was used to assess the strain level in the regrown layer.

Abstract: A radiation sensitive device comprising several rings and a middle section formed by a conventional charge coupled device. Drain means for radial draining of the charges generated in the circular sections by the incident radiation and drain means for the charge coupled device are provided. The device has a retina-like structure and can be advantageously applied in robotics.

Abstract: A thin film transistor is produced by applying onto a non-silicon foundation, a thin film of silicon semiconductor material under such conditions that polycrystalline or microcrystalline material is formed. Source and/or drain regions of doped semiconductor material are then formed onto the film; following by applying insulating material onto the film, and a gate region onto the insulating material. The source and/or drain regions are applied so that such regions have a crystalline structure that depends upon the crystalline structure of the underlying thin film. The resulting source and drain regions have high lateral conductivity so that source and drain contacts can be made with reduced cross-sectional areas. The method may employ a self-alignment process to simplify device production.

Abstract: An optical device provided with a junction region for reflecting radiation to be transmitted in the device, and a gate for controlling the electron density in said junction region, is fast and simple to manufacture.

Abstract: A system of measuring a state density in a semi-conductor element and a method using this system. The system measuring a state density in a semi-conductor element comprises a pulse generator and a control unit for controlling size and shape of the pulses, such as to be able to measure state densities in the band gap of the semi-conductor element.

Abstract: Included in a device for detecting radiation is an array of radiation-sensitive elements having respective outputs and circuitry for reading the outputs of such elements. The array of radiation-sensitive elements is preferably configured as a matrix of rows and columns of radiation-sensitive elements. Circuitry is provided to consecutively activate the columns; and circuitry is provided to generate a trigger signal depending on the occurrence of an amount of radiation above a threshold value. In this way the identity of a row in which an element is activated can be determined.

Abstract: A transducing device for sensing incident radiation includes an array of radiation sensitive elements, arranged in a matrix and interconnected to provide a plurality of interconnected rows and a plurality of interconnected columns of radiation sensitive elements. Comparator elements are connected to rows and columns of elements for comparing the magnitude of radiation received by the radiation sensitive elements to a predetermined threshold value. Encoding elements respond to outputs of the comparator elements for identifying radiation sensitive elements which have been exposed to radiation, including those elements where the radiation is maximum. The invention obviates the necessity of processing information from a large number of elements which do not hold useful information therein.