The formation of an amorphous interlayer between AlN and Si(111), which may degrade the film quality, is studied by varying the substrate temperature from 860 to 1010 °C in metal–organic chemical vapor deposition with a preflow of trimethylaluminum. The microstructure and chemistry of the amorphous interlayer have been investigated using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Cross-sectional TEM examinations show that AlN is directly in contact with Si for growth at 860 °C. At higher growth temperatures, an amorphous interlayer can be formed even if an AlN layer has been previously deposited on Si, and its thickness increases with growth temperature. The XPS depth profile across the amorphous interlayer formed at 1010 °C shows that both Al and N exhibit similar distribution, which gradually decreases toward the Si substrate whereas the Si concentration has the opposite distribution. The composition of the amorphous interlayer is determined to consist of Al, Si, and N.

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The attractive prospect for AlInN/GaN-based devices for high electron mobility transistors with advanced structure relies on high-quality AlInN epilayer. In this work, we demonstrate the growth of high-quality Al-rich AlInN films deposited on c-plane GaN substrate by metal-organic chemical vapor deposition. X-ray diffraction, scanning electron microscopy, and scanning transmission electron microscopy show that the films lattice-matched with GaN can have a very smooth surface with good crystallinity and uniform distribution of Al and In in AlInN.

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