Abstract: A semiconductor optical device such as a laser or semiconductor optical amplifier (SOA) based on an indium phosphide substrate or equivalent buffer layer. The active layer of the device is based on conventional InGaAs(P) alloy, but additionally includes N in order to increase the operating wavelength to greater than 1.5 ?m, preferably to a wavelength lying in the C- or L-band. The active layer composition may thus be denoted In1-xGaxAsyNzPp with x?0.48, y?1?z?p, z?0.05, p?0. The active layer may include a quantum well or multi-quantum wells in which case its thickness is preferably less than the critical thickness for lattice relaxation. In other embodiments the active layer is a “massive” layer with quasi-bulk properties. The active layer may advantageously be under tensile stress, preferably roughly between 1% and 2.2%, to manipulate the light and heavy hole bands. The active layer is typically bounded by barrier layers made of a suitable semiconductor alloy, such as AlInAs or InGaAs(P).

Abstract: A semiconductor optical device such as a laser or semiconductor optical amplifier (SOA) based on an indium phosphide substrate or equivalent buffer layer. The active layer of the device is based on conventional InGaAs(P) alloy, but additionally includes N in order to increase the operating wavelength to greater than 1.5 ?m, preferably to a wavelength lying in the C- or L-band. The active layer composition may thus be denoted In1-xGaxAsyNzPp with x?0.48, y?1-z-p, z?0.05, p?0. The active layer may include a quantum well or multi-quantum wells in which case its thickness is preferably less than the critical thickness for lattice relaxation. In other embodiments the active layer is a “massive” layer with quasi-bulk properties. The active layer may advantageously be under tensile stress, preferably roughly between 1% and 2.2%, to manipulate the light and heavy hole bands. The active layer is typically bounded by barrier layers made of a suitable semiconductor alloy, such as AlInAs or InGaAs(P).

Abstract: A process for preparing high density polyethylene in the gas phase comprising contacting a mixture comprising ethylene and one or more alpha-olefins with the supported reaction product of a bis-hydrocarbylsilyl chromate and a hydrocarbylaluminum compound or a hydrocarbyl boron compound in a fluidized bed reactor having a recycle gas line, under particularly defined polymerization conditions, including, but not limited to, the following provisos:(i) oxygen and/or another catalyst poison is introduced into the reactor in the range of about 0.005 to about 0.5 part by volume of catalyst poison per million parts by volume of ethylene; and(ii) a relatively low boiling inert hydrocarbon is introduced into the recycle gas line in an amount sufficient to raise the dew point of the recycle gas, which is comprised of alpha-olefins and other reactor gases, and the recycle gas is partially condensed and recycled to the reactor where it promotes cooling by evaporation.

Abstract: Process for producing a transistor, particularly a heterojunction bipolar transistor, of the type comprising the known stages consisting in producing layers forming the collector, base and emitter, as well as collector, base and emitter ohmic contacts. The emitter producing stage consists in depositing, on the base layer, two superposed layers making up the emitter, the first of which is a thin layer made up of a first material having a large energy gap, and the second made up of a second material also having a high energy gap. The base ohmic contact is deposited on the first layer of the emitter. The invention also relates to the transistors obtained.

Abstract: A monolithic semiconductor structure of a laser and a field effect transistor applicable to telecommunications comprises, on a semiinsulating substrate, a semiconductor layer of Ga.sub.1-x Al.sub.x As, a N-doped semiconductor layer of Ga.sub.1-y Al.sub.y As, a semiconductor layer of Ga.sub.1-z Al.sub.z As, in which x and z vary from 0.2 to 0.7 and y from 0 to 0.15 and a GaAs semiconductor layer. In these four layers are formed one type P region and two type N regions, the type P region and one of the type N regions defining between them the active zone of the laser and the two type N regions defining between them the active zone of the transistor, respectively forming the transistor source and drain. The P region of the laser is equipped with an electrode and the transistor source and drain with ohmic contacts. A process for making the structure as also disclosed.