Dimerization equilibrium of group 13 precursors for vapor deposition of thin films

Abstract

Group 13 precursors play a pivotal role in thin-film deposition processes such as atomic layer deposition (ALD) and chemical vapor deposition (CVD), which are essential for semiconductor and nanomaterial applications. However, their strong tendency to dimerize complicates interfacial interactions, challenging precise control over deposition processes. Current study investigates the dimerization tendencies of group 13 precursors using density functional theory (DFT) calculations. It was revealed that dimerization energies follow the trend Al > In ≈ Ga ≫ B, and alkoxy > amido > halogen > alkyl, so that Al- and alkoxy-based precursors would exhibit the highest propensity for dimerization. Our analysis demonstrates that dimerization energies strongly correlate with key properties of the monomer precursors, particularly the partial charge on the central atom and the covalency of the central element-ligand bonds. Monomeric fractions for group 13 precursors under deposition process conditions offer detailed insights into their dimerization behavior.