High-Curie-temperature Ga1-xMnxAs obtained by resistance-monitored annealing

We show that by annealing Ga1-xMnxAs thin films at temperatures significantly lower than in previous studies, and monitoring the resistivity during growth, an unprecedented high Curie temperature T-C and conductivity can be obtained. T-C is unambiguously determined to be 118 K for Mn concentration x = 0.05, 140, K for x = 0.06, and 120 K for x = 0.08. We also identify a clear correlation between T-C and the room temperatures conductivity. The results indicate that Curie temperatures significantly in excess of the current values are achievable with improvements in growth and post-growth annealing conditions. (C) 2002 American Institute of Physics.