Achieving high Curie temperature in (Ga, Mn)As

We study the effects of growth temperature, Ga: As ratio, and postgrowth annealing procedure on the Curie temperature T-C of (Ga, Mn) As layers grown by molecular beam epitaxy. We achieve the highest T-C values for growth temperatures very close to the two-dimensional-three-dimensional phase boundary. The increase in T-C, due to the removal of interstitial Mn by postgrowth annealing, is counteracted by a second process, which reduces T-C and which is more effective at higher annealing temperatures. Our results show that it is necessary to optimize the growth parameters and postgrowth annealing procedure to obtain the highest T-C. (C) 2008 American Institute of Physics.