AlN bulk single crystals were grown by spontaneous nucleation on the side wall of a hot pressed BN crucible, using both aluminum metal and AlN powder as source materials in an open system. Optimization of reactor pressure, temperature profile, and crucible design yielded AlN crystals with an a-plane platelet morphology. The crystals had low (11 (2) over bar0) omega rocking curve full-width at half-maximum values of 17-60 arcsecs indicative of their high crystalline quality. Further, the addition of 1% indium by weight to the source material was found to significantly influence growth. When All metal was used as a source material, the addition of indium to the source material resulted in an increase in the average crystal size by roughly an order of magnitude. When AlN powder was used as a source material, the indium addition resulted in a decrease in the total number of nucleation sites. The results show that the addition of indium is a promising method for improving the physical vapor transport growth of AlN. (C) 2008 Elsevier B.V. All rights reserved.