The invention relates to a process for preparing trialkylmetal compounds of the general formula R.sub.3M (where M=metal of group IIIA of the Periodic Table of the Elements (PTE), preferably gallium or indium, and R=C.sub.1-C.sub.5-alkyl, preferably methyl or ethyl). The process is based on the reaction of metal trichloride (MeCl.sub.3) with alkylaluminium sesquichloride (R.sub.3Al.sub.2Cl.sub.3) in the presence of at least one alkali metal halide as auxiliary base. The reaction mixture is heated to a temperature above 120 C. and the trialkylmetal compound is separated off from the reaction mixture via a separator, with partially alkylated products being at the same time recirculated to the reaction mixture. In a further step, the reaction mixture is heated to a maximum of 350 C. and the remaining alkylated and partially alkylated products are separated off. The products obtained in this way can optionally be recycled in the process. The process displays a high yield of trialkylmetal compound and also a high metal utilization; the products are used as precursors for MOCVD processes.

A gas inlet member of a CVD reactor includes a gas inlet housing having a gas distribution volume supplied with a process gas by a feed line and a multiplicity of gas lines, each formed as a tube and engaging openings of a gas outlet plate arranged in front of an inlet housing wall, and through which the process gas enters a process chamber. A coolant chamber adjoins the gas inlet housing wall and a coolant cools the gas inlet housing wall and outlet ends of the gas lines that are in heat-conductive contact with the gas inlet housing wall. The gas outlet plate is thereby thermally decoupled from the gas inlet housing wall such that the gas outlet plate, which is acted on by radiation heat coming from the process chamber, heats up more intensely than the outlet ends which extend into the openings of the gas outlet plate.

A gas phase nanowire growth apparatus including a reaction chamber (200), a first input and a second input (202 B, 202 A). The first input is located concentrically within the second input and the first and second input are configured such that a second fluid delivered from the second input provides a sheath between a first fluid delivered from the first input and a wall of the reaction chamber. An aerosol of catalyst particles may be used to grow the nanowires.

Embodiments include systems and methods for producing semiconductor wafers having reduced quantities of point defects. These systems and methods include a tunable ultraviolet (UV) light source, which is controlled to produce a raster of a UV light beam across a surface of a semiconductor wafer during epitaxial growth to dissociate point defects in the semiconductor wafer. In various embodiments, the tunable UV light source is configured external to a Metal Organic Chemical Vapor Deposition (MOCVD) chamber and controlled such that the UV light beam is directed though a window defined in a wall of the MOCVD chamber.

A vapor phase epitaxy method of growing a III-V layer with a doping profile that changes from n-doping to p-doping on a surface of a substrate or a preceding layer in a reaction chamber from the vapor phase of an epitaxial gas flow, comprising at least one carrier gas, a first precursor for a first element from main group III and at least one second precursor for a first element from main group V, and fed into the reaction chamber, wherein, when a first growth level is reached, an initial n-doping level is set by means of a ratio, leading to a p-doping, of a first mass flow of the first precursor to a second mass flow of the second precursor in the epitaxial gas flow and with the addition of a third mass flow of a third precursor for an n-type dopant to the epitaxial gas flow, subsequently.

A seed substrate for epitaxial growth has a support substrate, a planarizing layer of 0.5 to 3 m provided on the top surface of the support substrate, and a seed crystal layer provided on the top surface of the planarizing layer. The support substrate includes a core of group III nitride polycrystalline ceramics and a 0.05 to 1.5 m encapsulating layer that encapsulates the core. The seed crystal layer is provided by thin-film transfer of 0.1 to 1.5 m of the surface layer of Si<111> single crystal with oxidation-induced stacking faults (OSF) of 10 defects/cm.sup.2 or less. High-quality, inexpensive seed substrates with few crystal defects for epitaxial growth of epitaxial substrates and solid substrates of group III nitrides such as AlN, AlxGa1-xN (0<X<1) and GaN are obtained.