Pendeo-epitaxy of stress-free AlN layer on a profiled SiC/Si substrate

• A new method for chloride-hydride vapor phase pendeo-epitaxy of AlN is proposed
• Unstrained AlN layer is grown on a Si substrate with a nanoprofiled SiC buffer
• SiC made by substitution of atoms is well suited for the growth of AlN
• Dissolution of pores in silicon beneath the nano-SiC is revealed

A new approach to the pendeo-epitaxy of elastically-unstrained AlN films is developed. The AlN films are grown using chloride-hydride vapor phase epitaxy (HVPE) on a silicon substrate with specially synthesized and shaped buffer layer of nano-SiC (NSiC). This NSiC epitaxial layer is grown using a new technique based on the substitution of a part of silicon atoms by carbon ones in a 100–110 nm thick subsurface layer of the silicon substrate. The 2D array of ~ 200 nm in diameter wells with the depth of ~ 70 nm that is less than the NSiC layer thickness is formed on the NSiC surface using electron beam lithography followed by reactive ion etching, the period of the array is of 400 nm. In a single HVPE process we grew ~ 20 μm thick AlN film both on the shaped and smooth regions of the prepared substrate. The AlN films are examined with reflection high energy electron diffraction, X-ray diffractometry, Raman spectroscopy and scanning electron microscopy. We use the results of these measurements to compare residual elastic stresses in the AlN film grown on the shaped and smooth regions of the substrate. The film on the shaped part of the substrate is elastically-unstrained contrary to the smooth part where elastic stresses result in the formation of a textured AlN layer. The model of the AlN growth on shaped SiC/Si substrates prepared using the atomic substitution technique is proposed.