Abstract
A series of quaternary-diluted magnetic semiconductors, (In <sub>1-y</sub> Al <sub>y</sub> ) <sub>1-x</sub> Mn <sub>x</sub> As, have been successfully grown on InP substrates by low-temperature molecular beam epitaxy. The (In <sub>0.52</sub> Al <sub>0.48</sub> ) <sub>1-x</sub> Mn <sub>x</sub> As with x≤0.11 were grown on a nearly lattice-matched In <sub>0.52</sub> Al <sub>0.48</sub> As buffer, while the (In <sub>1-y</sub> Al <sub>y</sub> ) <sub>1-</sub> <sub>x</sub> Mn <sub>x</sub> As with a higher Mn content of 0.11<x≤0.18 were grown on a graded 3-layer In <sub>1-y</sub> Al <sub>y</sub> As buffer structure. The results of transmission electron microscopy and double-crystal X-ray diffraction reveal that all (In <sub>1-y</sub> Al <sub>y</sub> ) <sub>1-x</sub> Mn <sub>x</sub> As epilayers are single crystal with zincblende structure, and the lattice constant increases with increasing the Mn content. The magnetic measurements show that the (In <sub>1-y</sub> Al <sub>y</sub> ) <sub>1-x</sub> Mn <sub>x</sub> As semiconductors exhibit a paramagnetic-like state for x≤0.05 while a ferromagnetic state for x>0.05, and the Curie temperature of ferromagnetic (In <sub>1-y</sub> Al <sub>y</sub> ) <sub>1-</sub> <sub>x</sub> Mn <sub>x</sub> As increases with increasing Mn content. © 2006 Elsevier B.V. All rights reserved.