Max-planck-gesellschaft Zur F&#xf6;rderung Der Wissenschaften E. V.

Forschungsverbund Berlin E.v.

Createc Fischer & Co. Gmbh

Albrecht Fischer

Klaus Ploog

Tatsuro Watahiki

Erdmann Schubert

Wolfgang Braun

Yoshiji Horikoshi

Gerhard Abstreiter

Hans Fronius

Lars Jeurgens

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.

Process for evaporating high-melting materials

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.

Bipolar transistor with monoatomic base layer between emitter and

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.

Semiconductor photodetector devices with pairs of monoatomic layers

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.

Optically bistable semiconductor device with pairs of monoatomic layers

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.

Injection laser with at least one pair of monoatomic layers of doping

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.

Semiconductor devices with at least one monoatomic layer of doping atoms

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. Since the first layer has a low impurity concentration, the mobility of the charge carriers accumulating in the first layer is high, and the region containing the accumulated charge carriers can be used as channel of the field-effect transistor. Semiconductor bodies of the described type can also be used for other semiconductor devices, as opto-electronic devices and integrated circuits.

Heterostructure semiconductor device

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.

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Lochgau, Germany

Albrecht Fischer