A method of producing an adduct of an organometallic compound M(R.sup.1).sub.3 where M is either indium or gallium and (R.sup.1).sub.3 represents a plurality of organic radicals which may be the same or different, preferably methyl or ethyl groups, comprising electrolysing, using a sacrificial anode of the metal M, a solution containing components 1 and 2 as follows: component 1: one or more organomagnesium halide compounds R.sup.1 MgX where X is a halide radical selected from Cl, Br and I; where R.sup.1 represents one of the groups contained in (R.sup.1).sub.3 ; component 2: a polar aprotic liquid which is a solvent for component 1, e.g. tetrahydrofuran, diethyl ether, di-isopentyl ether, di-n-butyl ether, diphenyl ether or anisole. Preferably, the solution electrolysed additionally contains a third component, component 3, which is one or more organic halides R.sup.1 X.sub.A, where R.sup.1 is one of the groups contained in (R.sup.1).sub.3, X.sub.A is a halide radical preferably the same as X, the polar aprotic liquid being a solvent also for component 3.
Method for forming metal alkyl compounds by the direct combination of metal halide, lithium metal, and alkyl or aryl halide and for purifying metal alkyl compounds by repeated sublimation/pumping cycles. The method can be used to produce metal alkyl compounds which are substantially free of volatile impurities.
The present invention involves chemical compounds particularly useful for the preparation of thin films or layers of group 3/group 5 materials by MOCVD and other techniques. Such compounds may be represented as having the formulas [M(ER'R").sub.3 ].sub.n or [RM(ER'R").sub.2 ].sub.n or [R.sub.2 M(ER'R")].sub.n wherein M is aluminum, gallium or indium; E is phosphorus, arsenic or antimony; R, R', and R" are one or more of hydrogen, alkyl, aryl, alkyl-substituted aryl, cyclic alkyl, halide or other anionic group; and n is between about 1 and about 6.
A method of forming a crystalline compound semiconductor film comprises introducing into a crystal forming space housing a substrate on which a non-nucleation surface (S.sub.NDS) having a smaller nucleation density and a nucleation surface (S.sub.NDL) having a fine surface area sufficient for crystal growth only from a single nucleus and having a larger nucleation density (ND.sub.L) than the nucleation density (NDs) of the non-nucleation surface (S.sub.NDS) are arranged adjacent to each other an organometallic compound (VI) for supplying an element belonging to the group VI of Periodic Table represented by the general formula R.sub.1 --X.sub.n --R.sub.2 wherein n is an integer of 2 or more; R.sub.1 and R.sub.2 each represent alkyl; and X is S, Se or Te and a compound (II) for supplying an element belonging to the group II of Periodic Table in gas phase and applying crystal growth treatment according to the vapor phase method to the substrate to selectively form a crystalline group II-VI compound semiconductor film on the substrate.
