MBE growth of Mn-doped ZnSnAS2 thin films

ZnSnAs2 thin him doped with similar to 4% Mn was grown on (001) Inp substrates by all elemental solid source molecular beam epitaxy using the previously determined optimum substrate temperature of 300 degrees C and Zn:Sn:As-4 beam equivalent pressure ratio of 24:1:52. In this work, we have employed slower growth rate by halving the beam equivalent pressures of Zn, Sn and AS(4) we have used in Our earlier reports, while maintaining the same beam equivalent pressure ratio. From the high-resolution X-ray diffraction (HRXRD) data, the computed lattice constant a is 5.867 angstrom, which is in very good agreement with the reported lattice constant value of the bulk ZnSnAs2 chalcopyrite, suggesting that lowering the growth rate leads to a transition to a more chalcopyrite structure. The average composition ratio of Zn:Sn:As:Mn according to electron probe micro-analysis (EPMA) studies is 1:0.826:2.42:0.076. Hysteretic M-H Curves were obtained at 5, 100, 300 and 320K using a superconducting quantum interference device (SQUID) magnetometer. The Curie temperature was estimated to be similar to 330 K from the zero-field cooled temperature dependence of magnetization. The possible origin of this above-room-temperature ferromagnetism is discussed. (C) 2008 Elsevier B.V. All rights reserved.