Organometallic chemical vapour deposition of cobalt/indium thin films using the single-molecule precursors [(CO)₄Co]_aInR_3-a (R = CH₂CH₂CH₂NMe₂; a = 1-3)

Pure cobalt indium alloy thin films of the nominal compositions Co_0.50In_0.50, Co_0.66In_0.33 and Co_0.75In_0.25 were grown by OMCVD using volatile organometallic precursors of the general formula [(CO)₄Co]_a- InR_3-a [R = CH₂CH₂CH₂N(CH₃)₂; 1 : a = 1 ; 2: a = 2; 3: a = 3]. These organometallic compounds contain direct Co - In bonds and allow molecular control of the metal ratio of the grown films. The distribution of the metals were uniform throughout the films. The films were examined by AES depth profiling, SEM-EDX and X-ray diffraction. The phase composition of the films follows the phase diagram of the Co/In system, e.g. reflections of the crystalline phases Co, CoIn₂ and CoIn₃ were detected. Due to the multi-phase nature of the films, the coatings were unstable with respect to interfacial reactions with InP, e.g. the formation of CoP was observed by X-ray diffraction.