Abstract: An evaporator cell (100), in particular for evaporating a high-melting material like Si, comprises a first crucible (10) being adapted for receiving the material to be evaporated and providing a first evaporation volume, and a heating device (30) being arranged for heating the first crucible (10), wherein the first crucible (10) is arranged in a second crucible (20) surrounding the first crucible (10), so that a spacing (25) is formed between the first and second crucibles (10, 20), wherein the spacing (25) provides a second evaporation volume. Furthermore, a coating installation provided with at least one evaporator cell and a process for evaporating a high-melting material using the evaporator cell (100) are described.

Abstract: An evaporator cell (100), which is adapted for evaporating, in particular, a high-melting evaporant, includes a crucible (10) for receiving the evaporant, said crucible including a crucible bottom (11), a side wall (12) which extends in an axial direction of the crucible (10), and a crucible opening (13), and a heating device (20) with a heating resistor (21), which has a plurality of heating zones (21.1, 21.2), which are arranged on an outside surface of the crucible (10) and extend axially along the crucible (10), wherein the heating zones (21.1, 21.2) are equipped for multilateral resistance heating and/or electron beam heating of the crucible (10), and wherein the heating zones (21.1, 21.2) are constructed in such a manner that a heating current through the heating resistor (21), which is formed for example by a resistance sleeve, flows in parallel and in the same sense through all heating zones (21.1, 21.2). A method of operating the evaporator cell is also described.

Abstract: An evaporator cell for evaporating a high-melting material to be evaporated, comprises a crucible for receiving the material to be evaporated, and a heating device with a heating resistor for the resistance heating of the crucible, the heating resistor being provided as an electron emitter for the electron beam heating of the crucible.

Abstract: A process for the evaporation of a high-melting material in an evaporator cell having a crucible for receiving the material to be evaporated, and a heating device with a heating resistor for the resistance heating of the crucible, the heating resistor being provided as an electron emitter for the electron beam heating of the crucible.

Abstract: A molecular beam epitaxy (MBE) device (100) which is designed for the reactive deposition of a group III nitride compound semiconductor comprises a vacuum chamber (10) which comprises at least one molecular beam source (11) and at least one injector (12) designed to inject ammonia into the vacuum chamber (10), a first cold trap device (20) comprising at least one cold trap (21, 22) designed to condense excess ammonia, a pump device (30) comprising at least one pump (31, 33, 35) designed to evacuate the vacuum chamber (10), and a barrier device (40), by means of which the first cold trap device (20) can be separated from the vacuum chamber (10). A method for operating an MBE device is also described.

Abstract: An evaporator cell, in particular for evaporating a high-melting material to be evaporated, comprises a crucible for receiving the material to be evaporated, and a heating device with a heating resistor for the resistance heating of the crucible, the heating resistor being provided as an electron emitter for the electron beam heating of the crucible. A process for the evaporation of a high-melting material to be evaporated is also described.

Abstract: A semiconductor device consisting of epitaxial material is provided with at least one monoatomic layer of doping atoms, i.e. with a layer which is just one atom thick. A preferred device is a bipolar transistor in which case the Dirac-delta doped p-type layer 38 is directly between n-type collector and emitter layers (32, 33). The bipolar transistor described herein has an extremely low base width and is capable of operating at high frequencies.

Abstract: A semiconductor light wave detector which has a first layer of a highly doped n-type semiconducting substrate, a second layer of a highly doped n-type semiconducting material, a third layer of a distinct intrinsic semiconducting material and a fourth layer of a highly doped n-type semiconducting material similar to the second layer. First and second electrical connections are provided to the fourth layer and to at least one of the first and second layers. A plurality of pairs of Dirac-delta doped monoatomic layers are in the third layer, with the first monoatomic layer of each pair being a layer of donors and with the second monoatomic layer of each pair being acceptors spaced from the donor layer and positioned on the side thereof facing the fourth layer.

Abstract: An optically bistable semiconductor device which has a doped or undoped gallium arsenide substrate and a series of alternating n-type and p-type Dirac-delta doped monoatomic layers formed on the substrate. Each Dirac-delta doped monoatomic layer is separated from the next adjacent Dirac-delta doped monoatomic layer by a layer of pure, undoped intrinsic semiconductor material such as gallium arsenide.

Abstract: A semiconductor device consisting of epitaxial material is provided with at least one monoatomic layer of doping atoms, i.e. with a layer which is just one atom thick. A particularly preferred device is injection laser in which case the Dirac-delta doped layers 45 and 46 are within intrinsic layer 43. The injection laser is constructed with a hetero structure.

Abstract: A semiconductor device consisting of epitaxial material is provided with at least one monoatomic layer of doping atoms, i.e. with a layer which is just one atom thick. A particularly preferred device is a field effect transistor in which case the Dirac-delta doped layer 13 extends between the source and drain zones (18, 19) respectively. The field effect transistor can be constructed either with a homogeneous structure or with a hetero structure or with a superlattice structure. The field effect transistors described herein have a high transconductance and are capable of operating at high current densities.

Abstract: A heterostructure semiconductor device as a Schottky gate field-effect tristor comprises a semiconductor body including first and second layers made of different semiconductor materials, as gallium arsenide and aluminium gallium arsenide. A narrow heterojunction is formed between the layers. The material of the first layer is pure and comprises a minimum of defects. The second layer comprises a doping material, the concentration of which being at least one order of magnitude higher than the concentration of any doping or impurity material present in the first layer. The semiconductor and doping materials are chosen such that the energy levels occupied by the shallow doping material atoms in said second layer have an energetically more unfavorable position than an adjacent of the energy bands of the first layer so that free charge carriers from the doped second layer can migrate in an adjacent region of the first layer.

Abstract: A new method for GaAs substrate preparation which significantly reduces the ormation of oval defects during MBE growth of selectively doped n-Al.sub.x Ga.sub.1-x As/GaAs heterostructures. The method simply requires treatment in H.sub.2 SO.sub.4 after mechano-chemical polishing in NaOCl solution and generation of a protective surface oxide during in soldering. Routinely a density of oval defects of less than 200 cm.sup.-2 is achieved for 2-.mu.m thick heterostructures. The efficiency of the new preparation procedure is demonstrated by 2DEG mobilities in excess of 10.sup.6 cm.sup.2 /Vs at 6K obtained with a spacer width as narrow as 18 nm.