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

Abstract

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 °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°C and 240⩽T_RI°C⩽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.