Growth of high-quality AlN epitaxial film by optimizing the Si substrate surface

摘要

Graphical abstractAFM images for cleaned Si substrates for (a) Sample 1, (b) Sample 2, (c) Sample 3, (d) Sample 4, and (e) Sample 5; and the AFM images for corresponding AlN epitaxial films for (f) Sample 1, (g) Sample 2, (h) Sample 3, (i) Sample 4, and (j) Sample 5.Display OmittedHighlights•High-quality AlN epitaxial films have been grown on Si substrates by MOCVD.•Effect of the Si substrate surface on the property of AlN epitaxial films is carefully studied.•The corresponding mechanism is proposed to interpret the effect of Si substrate surface on the property of AlN epitaxial films.AbstractHigh-quality AlN epitaxial films have been grown on Si substrates by optimizing the hydrofluoric acid (HF) solution for cleaning of Si substrates. Effect of the Si substrate surface on the surface morphology and structural property of AlN epitaxial films is investigated in detail. It is revealed that as the concentration of HF solution increases from 0 to 2.0%, the surface morphology and the crystalline quality are initially improved and then get worse, and show an optimized value at 1.5%. The as-grown ∼200nm-thick AlN epitaxial films on Si substrates grown with HF solution of 1.5% reveal the root-mean-square (RMS) surface roughness of 0.49nm and the full-width at half-maximum for AlN(0002) X-ray rocking curve of 0.35°, indicating the smooth surface morphology and the high crystalline quality. The corresponding mechanism is proposed to interpret the effect of Si substrate surface on surface morphology and structural property of AlN epitaxial films, and provides an effective approach for the perspective fabrication of AlN-based devices.