Relation among concentrations of incorporated Mn atoms, ionized Mn acceptors, and holes in p-(Ga,Mn)As epilayers

The amount of ionized Mn acceptors in various p-type Mn-doped GaAs epilayers grown at high (Ts=580 °C) and low (Ts=250 °C) substrate temperatures has been evaluated by electrochemical capacitance-voltage measurements, and has been compared systematically with concentrations of incorporated Mn atoms and holes for a wide range of Mn concentrations (NMn=1017–1021 cm−3). Low-Ts samples are found to be classified into three different types: (a) a highly resistive, strongly compensated region at NMn⩽1018 cm−3, (b) a low-resistance, fully ionized region for NMn between 5×1018 and 1020 cm−3 in which impurity conduction dominates, and (c) a magnetic, low-resistance region for NMn⩾2×1020 cm−3 in which magnetism and carrier transport are strongly correlated. A quantitative assessment of the anomalous Hall effect at room temperature is also carried out.