A dual BN/AlN capping layer has been developed for annealing implanted SiC up to a temperature of at least 1700 degreesC. The AlN is used as a protective layer on SiC because it is chemically inert on the material and can be removed selectively with a warm KOH etch, while the BN layer prevents the AlN from evaporating at temperatures above 1600 degreesC. Prior to etching off the AlN film, the BN film is ion milled off. The BN film appears to be an excellent cap as the hexagonal phases present, hexagonal (hBN) and turbostratic (tBN), are stable to temperatures in excess of 2000 degreesC. After annealing, the BN forms a tight seal on top of the AlN in a dense epitaxial h-BN phase, with a t-BN layer forming above the hBN. The tBN layer should be able to accommodate strains caused by lattice mismatch and differences in the thermal coefficients of expansion because it, like graphite, forms strong sp(2) bonds in the basal plane, but contains loosely bonded basal planes that easily slip over each other. (C) 2002 Elsevier Science Ltd. All rights reserved.