Method for vapor phase deposition of gallium nitride film

#The present invention relates to methods of depositing III-V films, particularly wherein the Group III element is gallium and the Group V element is selected from arsenic, phosphorus, and nitrogen.

#The present invention relates further to novel adducts of gallane (GaH.sub.3) with lower alkyl amines.

#The 1:1 adduct of gallane (gallium hydride) and trimethylamine is known. Its preparation is taught in Shriver, et al., Trihydrido(trimethylamine)gallium", Inorganic Syntheses, Vol. 17, pages 42-44 (1980). Preparation of the lithium gallium hydride starting material recited in the foregoing article is taught in Shirk, et al., Lithium tetrahydridogallate," Inorganic Syntheses, Vol. 17, pages 45-47 (1980). No use for the adduct is reported in these articles. The adduct has a melting point of 69.degree. C., and is sublimable. Consequently, it is not an ideal candidate for use in metal organic chemical vapor deposition (MOCVD), for which compounds in liquid form at or near room temperature are desired. Also, higher alkyl compounds analogous to this adduct are not known.

#In this Example, GaH.sub.3 N(CH.sub.2 CH.sub.3).sub.3 was prepared. The first stage reaction was as follows:

#4 LiH+GaCl.sub.3 .fwdarw.LiGaH.sub.4 +3 LiCl

#A one liter, three-neck flask was connected to a source of nitrogen, an addition funnel, and a flexible tube. A 25 gram ampoule of gallium chloride was opened and inverted in one neck of the flask. The ampoule was heated with a heat gun to melt the gallium chloride, which dripped into the flask. The flask was cooled to -78.degree. C., then about 500 ml. of diethyl ether were added. The flask contents were warmed enough (by removing the cold bath temporarily) to dissolve the gallium trichloride (while stirring the mixture with a magnetic stirrer). When the contents were dissolved, the flask was returned to -78.degree. C. 20 grams (2.53 mols.) of lithium hydride powder were added by pouring it from a small flask connected to the reaction pot with the flexible tube, while stirring the reaction mixture. After all the lithium hydride had been added, the dry ice bath was removed and the reaction mixture allowed to slowly warm to room temperature. The mixture was stirred overnight at room temperature, then filtered to remove lithium chloride and excess lithium hydride. The lithium gallium hydride was not isolated.