The microstructures and electrical properties of 8 4% nitrogen-doped GeTe and GeBi(6 at.%)Te films thermally annealed in N(2) atmosphere were investigated With the addition of Bi to N-doped GeTe films the initial crystallization temperature was reduced and crystallization speed slowed The N-doped GeBiTe films showed a rapid increase in crystallite size compared to the N-doped GeTe films The formation energy of the nucleus may be lower due to the Bi atoms and the growth speed may be slower (C) 2010 Elsevier B V All rights reserved