Design and self-catalytic mechanism of aluminum precursors bearing amino ligands for Al2S3 atomic layer deposition

Abstract

As a unique nanotechnology, atomic layer deposition (ALD) has been extensively used for the preparation of various nanomaterials. An effective precursor is a prerequisite to ALD success. Herein, we designed and introduced alkyl, hydrogen, halide, alkoxy and amino ligands to aluminum precursors and investigated reaction mechanisms of Al2S3 ALD through density functional calculations. The results show that aluminum precursors with alkyl, hydrogen and halide ligands are kinetically disadvantageous and with alkoxy groups are thermodynamically unfavorable and Al precursors bearing amino groups are thermodynamically and kinetically favorable for Al2S3 ALD. The activity of trimethylaluminum (TMA) on the sulfydrylated surface is lower than that on the hydroxylated surface. The reaction barriers of the aluminum precursors bearing amino ligands on the sulfydrylated surface are obviously lower than that of TMA. Similarly, the barrier of the H2S reaction on the aminated surface is much lower than that on the methylated surface. All of the amino groups have a self-catalytic role and accelerate the reaction of Al2S3 ALD. These insights into aluminum precursors bearing amino ligands for Al2S3 ALD can provide theoreticalguidance for the discovery of new precursors and the ALD preparation of other aluminum and sulfur compounds.