In situ study of a strontium ?-diketonate precursor for thin-film growth by atomic layer epitaxy

Precursor properties of Sr(thd)2 (thd = 2,2,6,6-tetramethyl heptane-3,5-dione) have been investigated using in situ mass monitoring of thin films during atomic layer epitaxy growth cycles. H2O and H2S were used as the other source materials. The Sr(thd)2 source temperature, T(s), significantly affects the growth rate. At T(S) = 240-270-degrees-C, a decrease of growth rate and in some cases even etching of the grown film takes place. These phenomena can be explained by the decomposition of Sr(thd)2, which also explains the dependence of the growth rate on the reactor temperature, T(R), observed when T(S) < 240-degrees-C and 240 less-than-or-equal-to T(R)/degrees-C less-than-or-equal-to 400. The growth experiments were complemented and the conclusions supported by separately studying (by mass spectrometry thermogravimetry, and differential thermal analysis) the thermal stability and fractionation of the precursor.