Enhanced pseudo-atomic layer deposition of antimony telluride thin films by co-injecting NH3 gas with both precursors

Abstract

This work proposed an enhanced deposition method of antimony telluride (Sb₂Te₃) thin films, which allowed facile growth at high temperatures (> 150 °C). The enhancement was enabled by co-injecting NH₃ gas with Sb- and Te-precursors. An in-depth analysis of the deposition mechanism revealed that the Sb-precursor (Sb(OC₂H₅)₃) and NH₃ gas reacted to form an Sb–O/Sb–Sb layer, which was then converted to Sb₂Te₃ upon the injection of the Te-precursor (Te(Si(CH₃)₃)₂) and NH₃ gas. Thus, a pseudo-atomic layer deposition (pseudo-ALD) component was incorporated into the deposition process, which led to growth per cycle (GPC) enhancement. The deposited films were of high density, contained low amounts of impurities, and had a preferential out-of-plane c-axis orientation when deposited on SiO₂ substrates. Despite the pseudo-ALD process, conformal deposition on extreme nanoscale structures was demonstrated.