Epitaxial growth mechanism of pulsed laser deposited AlN films on Si (111) substrates

Abstract

The epitaxial growth mechanism and causes of dislocation formation in AlN films on a Si substrate by pulsed laser deposition (PLD) are comprehensively proposed. Due to the high energetic effect and pulsed effect of PLD, the epitaxial process of AlN film growth on Si (111) by PLD is a two-dimensional layer-by-layer growth regime in relation to the strain–relaxation mechanisms. Three PLD sub-stages of the epitaxial process for AlN films on a Si substrate have been suggested and interpreted in detail. Under optimum growth conditions, the film exhibits 1.5 nm-thick single-crystalline AlN interfacial layers with a high density of dislocations, rather than an amorphous SiN_x layer. On the contrary, severe interfacial reaction and an AlSiN layer were found at the AlN/Si (111) interface under non-optimal growth conditions, which is derived from the interfacial interdiffusion and penetration between active Si atoms and AlN species, resulting in a high density of dislocations and defects at the AlN/Si (111) interface.