Abstract A method of depositing a group III element - group V element compound or alloy on a hot substrate using a metal organic chemical vapour 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.
A method of depositing a group III - group V compound on a heated substrate which comprises conveying an alkyl derivative of the group III element, modified to be a weaker Lewis acid by the donation of electron density, in admixture with the hydride of the group V compound.
Claim 2
Independent Claim
49 words
A method of depositing a group III - group V compound on a heated substrate which comprises conveying an alkyl derivative of the group III element, modified to be a weaker Lewis acid by the donation of electron density, in admixture with the hydride of the group V compound.
Claim 3
Dependent Claim
59 words
A method as claimed in Claim 1 wherein the alkyl derivative of the desired group III element is combined with an alkyl derivative of a group V element, a Lewis Base, thereby forming a volatile adduct, and thereafter conveying the volatile adduct and the hydride of the desired group V element as vapour to impinge upon a hot substrate.
Claim 4
Dependent Claim
30 words
A method as claimed in Claim 1 wherein the modified derivative is prepared by replacing an alkyl group on a group III element alkyl derivative with an electron donating group.
Claim 5
Independent Claim
23 words
A method as claimed in any of the preceding claims wherein the modified derivative is prepared immediately before conveying it to the substrate.
Claim 6
Dependent Claim
29 words
A method as claimed in Claim 3 wherein the modified derivative is prepared and isolated prior to the reaction with the group V hydride and deposition on the substrate.
Claim 7
Independent Claim
17 words
A method as claimed in any of the preceding claims wherein the group III element is indium.
Claim 8
Independent Claim
71 words
A method as claimed in any of the preceding claims wherein a vapour stream containing the alkyl derivative of the group III element is mixed with a vapour stream of the compound which donates electron density thereby forming the modified ' derivative and the vapour stream containing the said derivative is mixed with a vapour stream containing the hydride of the group V compound, the mixed streams then contacting the substrate.
Claim 9
Dependent Claim
27 words
A method as claimed in Claim 6 wherein the first mixed vapour stream is maintained at a temperature above ambient to avoid condensing of the modified derivative.
Claim 10
Dependent Claim
21 words
A method as claimed in either Claim ? or Claim 8 wherein all the gas streams contain an excess of hydrogen.
Claim 11
Independent Claim
26 words
A method as claimed in any of the preceding claims wherein a mixture of group III alkyl derivatives is modified prior to conveying to the substrate.
Claim 12
Independent Claim
22 words
A method as claimed in any of the preceding claims wherein a mixture of group V hydrides is conveyed to the substrate.