Abstract: A method for forming a layer of a Group II or III fluoride on a semiconductor substrate (e.g. as epitaxial insulating layer) comprising vaporising a precursor (I), where M is Be, Ca, Sr, Ba or lanthanide, b and d are 0 or 1. A, B, C and D are independently (IIA) or (IIB), X being O, S, NR, PR where R is H, alkyl, perfluoroalkyl; Y is perfluoroalkyl, fluoroalkenyl, fluoroalkylamine or fluoroalkenylamine; Z is H, F, alkyl, perfluoroalkyl or perfluoroalkenyl; and then decomposing the precursor vapor to form M fluoride. A preferred precursor for CaF.sub.2 is a calcium 1,1,1,5,5,5-hexafluor-2,4-pentanedione complex where b and d are 0.

Abstract: A method of providing a reagent into a chemical process said provision being in the vapor phase and at a controlled mass flow rate wherein the method comprises:(a) providing a gas stream which contains a gaseous phase complexing agent for the reagent said complexing agent being provided at a controlled partial vapor pressure in said gas stream;(b) providing a primary source of the reagent in a reservoir which is connected to the gas stream via a diffusion path;(c) causing the gaseous phase complexing agent to diffuse into the reservoir at a mass flow rate controlled by its partial pressure in the gas stream;(d) causing the gaseous phase complexing agent in the reservoir to react with the primary source to generate a gaseous phase complex of the reagent and the gaseous phase complexing agent, said generation being, in the steady state, at a rate equivalent to the rate of inflow of said complexing agent;(e) causing the gaseous phase complex to diffuse out of the reservoir into the gas stream at a rate, in the s

Abstract: A method for forming a layer of a Group II or III fluoride on a semiconductor substrate (e.g. as epitaxial insulating layer) comprising vaporizing a precursor (I), where M is Be, Ca, Sr, Ba or lanthanide, b and d are 0 or 1. A, B, C and D are independently (IIA) or (IIB), X being O, S, NR, PR where R is H, alkyl, perfluoroalkyl; Y is perfluoroalkyl, fluoroalkenyl, fluoroalkylamine or fluoroalkenylamine; Z is H, F, alkyl, perfluoroalkyl or perfluoroalkenyl; and then decomposing the precursor vapor to form M fluoride. A preferred precursor for calcium fluoride is calcium 1,1,1,5,5,5-hexafluor-2,4-pentanedione complex where b and d are 0.

Abstract: A method of preparing a metal alkyl of formula (R.sub.3 M).sub.x where R.sub.3 represents three alkyl groups R which may be the same or different, M represents a Group III metallic element and x is 1 or 2, which method comprises (a) forming a trialkyl adduct of formula (R.sub.3 M).sub.y.L wherein L represents an aryl-containing Group V, preferably phosphorus, donor ligand provided by an organic Lewis base which is stable at 20.degree. C., and wherein Y is an integer equal to the number of Group V atoms presents in the ligand, and (b) heating the adduct to provide thermal dissociation thereof thereby releasing the alkyl as a gaseous product.

Abstract: A method of depositing a group III element--group V element compound or alloy on a hot substrate using a metal organic chemical vapor deposition procedure. Attempts to apply an MOCVD procedure to the production of a group III element--group V element compound from alkyl derivatives of group III elements which are strong Lewis acids and group V element hydrides have met with limited success. This is because the reactants react in the cold gas phase to form an involatile polymer which does not give the required product on the hot substrate. The present invention proposes modifying the alkyl derivative of the group III element to be a weaker Lewis acid. This can be achieved by either substituting an electron donating group for one of the alkyl groups bonded to the group III element or by combining the group III element alkyl derivative with an alkyl derivative of a group V element thereby forming a volatile compound.

Abstract: A Group III element Q selected from gallium, indium and thallium containing a Group VI element X selected from oxygen, sulphur, selenium and tellurium as an impurity can be purified by adding, to molten Q, an element M capable of forming with X a stable solid compound substantially insoluble in liquid Q. The stable solid compound can be separated and the purified Q used in the epitaxial growth of a semiconductor material such as indium phosphide. Alternatively, in a process for the epitaxial growth of a semiconductor compound of Q in molten Q, X can be removed in situ by the addition of a suitable element of the M-type.

Abstract: Semiconductor compounds which are alloys of group III-V compounds are grown by a liquid phase epitaxy method which includes heating growth apparatus in a reducing atmosphere while maintaining a solvent for the compound, a source of the group III-V compound and another element of the alloy separate from each other. After heating to reduce oxides, the element is added to the solvent, the source is brought into contact with the solvent and the resulting solution is brought into contact with a substrate to effect growth of the compound. Apparatus for carrying out the method is also described.

Abstract: The surface of a semiconductor is prepared by electrolytically removing the surface of the semiconductor. A two component electrolyte is used. A first component forms an oxide on the surface of the semiconductor and the second component dissolves the oxide.

Abstract: The electrochemical measuring technique of the present invention employs, as the barrier material, a concentrated electrolyte, which also forms a medium for the controlled dissolution of a surface of the semiconductor so as to provide a continuous depth profile. The depth profile characteristic may be determined by capacitance-voltage measurements on n-type bulk GaAs, using KOH as the electrolyte.

Abstract: A method of preparing a methyl alkyl of formula (R.sub.3 M).sub.x where R.sub.3 represents three alkyl groups R which may be the same or different, M represents a Group III metallic element and x is 1 or 2, which method comprises (a) forming a trialkyl adduct of formula (R.sub.3 M).sub.y. L wherein L represents an aryl-containing Group V, preferably phosphorus, donor ligand provided by an organic Lewis base which is stable at 20.degree. C., and wherein Y is an integer equal to the number of Group V atoms presents in the ligand, and (b) heating the adduct to provide thermal dissociation thereof thereby releasing the alkyl as a gaseous product.