ABSTRACTSecondary or abnormal grain growth has been observed in ultrathin films of silicon (<120nm) that were heavily doped with phosphorous or arsenic. This grain growth leads to grains which are much larger than the film thickness (>50x) and which have uniform (111) texture. This abnormal grain growth is believed to be driven, in part, by surface energy minimization and hence is termed surface-energy-driven secondary grain growth.It was found that n-type dopants, phosphorous and arsenic, markedly enhance the rate of secondary grain growth as seen through a lowering of the temperature required for significant growth. On the other hand, boron (a p-type dopant) appears to neither markedly increase nor decrease the rate of grain growth. Enhancement caused by phosphorous or arsenic is thought to stem from increases in the mobility of the grain boundaries. Enhancement of grain boundary mobility was found to be compensated (reduced or eliminated) by additional doping with boron.