High-Quality AlN Grown by a Combination of Substrate Pretreatment and Periodic Growth Mode Control

Thegrowth of high-quality AlN films has always been the focusof research. Combined with NH3 in situ pretreatment beforegrowth, with optimized growth conditions, we demonstrated a periodicgrowth method, which alternates between three-dimensional (3D) growthmode and two-dimensional (2D) growth mode, to grow a thick crack-freeAlN film with good crystal quality on the on-axis 4H-SiC substrateby metal-organic chemical vapor deposition (MOCVD). X-ray rockingcurves (XRCs) indicated that full width at half-maximum (FWHM) ofthe (0002) and (10-12) reflections were 241.3 '' and 474.4 '',respectively. The film thickness was over 1.4 mu m. Lattice constantand residual stress results showed residual compressive stress inthe sample. The periodic two-step growth and substrate pretreatmentboth play an important role in controlling the residual stress offilms to avoid cracking. This work can serve as an important referencefor growing high-quality crack-free AlN on SiC. The periodic two-step growth and substratepretreatmentboth play an important role in controlling the residual stress offilms to avoid cracking.