Fabrication of Sb_2Te_3 and Bi_2Te_3 multilayer composite films by Atomic Layer Deposition

摘要

Atomic Layer Deposition (ALD) growth of antimony telluride Sb_2Te_3 and bismuth telluride Bi_2Te_3 multilayer composite films has been investigated. We have fabricated Sb_2Te_3 and Bi_2Te_3 thin films using (trimethylsilyl) telluride ((Me_3Si)_2Te), bismuth trichloride (BiCl_3) and antimony trichloride (SbCl_3) as precursors for telluride, bismuth and antimony respectively. Both metal tellurides exhibit Volmer Weber Island growth mode and have characteristic hexagonal crystallites, which are telluride terminated at the surface making chemisorption rather challenging. We found that the presence of OH~- bonds at the surface promotes ALD thin film growth by providing suitable nucleation sites and prevents delamination of the hexagonal platelet shaped crystallites. The use of longer exposure times of precursors during the ALD process increases chemisorptions and interface oxidation aids in the creation of nucleation sites. We present surface morphology studies using FE-SEM analysis.