Abstract: A photodetector which can be operated in two wavelength ranges and is comprised of two detectors (A, B) arranged one on top of the other. A Si Schottky diode forms detector A which absorbs light in a region .lambda.<0.9 .mu.m. Longer-waved light (1 .mu.m<.lambda.<2 .mu.m) is absorbed in detector B which is comprised of an Si/SiGe pn-diode. To increase the efficiency, detector B is made with an integrated resonator. A further increase of the efficiency of the photodetector is accomplished through the mounting of a Bragg reflector on the absorbing layer of detector B.

Abstract: A method of fabricating an HBT using differential epitaxy. By using an emitter mask and an exside-inside spacer structure, a self-aligned fabrication of an emitter contact and a base contact is carried out. The emitter contact layer is made from amorphous silicon. Since the entire process sequence is very temperature-stable and can be carried out at lower implantation energies than conventional methods, HBT's having a high layer quality can be fabricated by the method of the invention which is suitable for mass production and with which high oscillation frequencies can be accomplished.

Abstract: An apparatus for the production and/or treatment of particles has a gas circulation possessing a process chamber and a gas circulation device and at least one spray nozzle. The latter has a nozzle body with a liquid outlet and a gas passage surrounding the nozzle body at the liquid outlet and entering the process chamber. For the production and/or treatment of particles, the pressure in the gas circulation is reduced to a value below the ambient air pressure by a suction device and gas is circulated by the gas circulation device so that gas flows upward through the process chamber. In addition, a liquid is sprayed in the process chamber from time to time through the spray nozzle and at the same time gas is passed from a branch of the gas circulation to the gas passage of the spray nozzle and through the latter into the process chamber. This gas protects the spray nozzle from the adhesion of sprayed liquid without additional gas entering the gas circulation from outside.

Abstract: A process for preparing a bipolar transistor for very high frequencies is described, which is especially advantageous for the preparation of heterobipolar transistors and leads to components with low parasitic capacities and low base lead resistance. The process includes forming a structured first layer with collector zone and insulation areas surrounding the collector zone on a monocrystalline lead layer. A series of monocrystalline transistor layers are grown on the first layer over the collector zone by differential epitaxy and a series of polycrystalline layers is grown at the same time over the insulation areas. A series of polycrystalline layers is designed as a base lead.

Abstract: The invention relates to a method in particular for manufacturing bipolar transistors. By applying selective epitaxy methods and by using self-adjusting techniques, the process sequence is shortened and the transistor properties are improved.

Abstract: A process for producing monolithically integrated multifunction circuit arrangements. A substrate having an integrated circuit formed therein is provided, and further multilayer semiconductor components and the corresponding electrical leads are arranged on top of one another on the substrate surface. The multilayer semiconductor components and the electrical leads are produced from an epitaxially grown semiconductor layer sequence.