The Post Office

British Telecommunications Public Limited Company

The Secretary of State for Defence in Her Britannic Majesty's Government

British Telecommunications Corporation

Marc M Faktor

Rodney H Moss

Donald C Bradley

John Haigh

Ean Grant Bremner

Thomas Ambridge

John Leslie Stevenson

Dario M Frigo

Halina Chudzynska

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:

Reagent source

Preparation of metal alkyls

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. Both the substituted alkyl derivative of the group III element and the volatile alkylated group III-V compound give the required product when used in admixture with a group V element hydride in an MOCVD process.

Metal organic vapor deposition procedure for preparing group III--V

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.

Semiconductor materials

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.

Growth of semiconductor compounds

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.

Electrolytic etch preparation of semiconductor surfaces

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.

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Bushey Heath, United Kingdom

Marc M Faktor