Achieving high Curie temperature in (Ga,Mn)As

Abstract

We study the effects of growth temperature, Ga:As ratio, and postgrowth annealing procedure on the Curie temperature TC of (Ga,Mn)As layers grown by molecular beam epitaxy. We achieve the highest TC values for growth temperatures very close to the two-dimensional–three-dimensional phase boundary. The increase in TC, due to the removal of interstitial Mn by postgrowth annealing, is counteracted by a second process, which reduces TC 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 TC.