Figure 2: Individual optimization for each nominal Mn doping of the growth temperature and of the annealing temperature and time.
(a) Optimal growth temperature TG as a function of the nominal Mn-doping x. (b) Dependence of the Curie temperature TC on the annealing time for two annealing temperatures TA=160 °C (red points) and 140 °C (black points) in a 15-nm-thick (Ga,Mn)As epilayer with 13% nominal Mn doping grown at optimal TG. (c,d) Resistivity ρ(T) and temperature derivative of the resistivity normalized to the peak value (dρ/dT)* in the x=13% epilayer grown at optimal TG in the as-grown state (black line), for optimal TA and annealing time 0.5 h (blue line) and for optimal TA and optimal annealing time of 8 h (red line). (e,f) Same as panels c and d for a x=13% epilayer grown at 10 °C below optimal TG; ρ(T) for the as-grown state and for the annealing time 0.5 h are multiplied by the numerical factors depicted in the figure for clarity; (dρ/dT)* is not plotted for the as-grown insulating and paramagnetic sample.
