Preparation of Group II metal alkyls
AssigneeThe Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
InventorsJohn B. Mullin, John C. Hamilton, Elisabeth D. Orrell, Philip R. Jacobs, Deodattta V. Shenai-Khatkhate
Life of this patent
Estimating the term…
Abstract
A method of preparing high purity dimethyl cadmium or dimethyl zinc suitable for use in the deposition of Group II-VI epitaxial layers, which consists of forming an adduct of the metal alkyl with a non-chelating tertiary amine containing at least two tertiary amino groups per amine molecule, and subsequently dissociating the adduct to liberate the metal alkyl as a vapor. The adducts formed during the preparative method are found to dissociate readily on heating and yet are substantially involatile and so do not contaminate the liberated metal alkyl. A preferred amine suitable for use in the preparative method is 4,4' bipyridyl.
Claims15
A method of preparing a metal alkyl of general formula MR.sup.1 R.sup.2, in which M :s selected from cadmium and zinc and R.sup.1 and R.sup.2 are independently selected from C.sub.1 -C.sub.8 alkyl. which comprises the steps of
- (a) forming an adduct of the metal alkyl with a Lewis base comprising a tertiary amine having at least two tertiary amino groups per molecule whose nitrogen atoms are capable of co-ordinating with M, and
- (b) dissociating the adduct to liberate the metal alkyl at a pressure P and at a temperature below the sublimation temperature or boiling point of the tertiary amine at pressure P as the case may be, characterised in that the tertiary amine has a molecular structure whose nitrogen atoms, for geometric reasons, co-ordinate with different atoms M such that the adduct formed has a vapour pressure of less than 1.33 Pa at its dissociation temperature at that pressure.
Dependencies are inferred from the claim text.