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Epitaxial growth of high curie temperature ge1−xmnx quantum dots on si(001) by self assembly

We also evidence that the ferromagnetic ordering in Ge1−xMnx quantum dots persists up to a temperature higher 320 K. It is believed that single-crystalline quantum dots exhibiting a high Curie temperature are potential candidates for the realization of nanoscale spintronic devices. | Communications in Physics, Vol. 24, No. 1 (2014), pp. 69-77 EPITAXIAL GROWTH OF HIGH CURIE-TEMPERATURE Ge1−x Mnx QUANTUM DOTS ON Si(001) BY SELF-ASSEMBLY LUONG THI KIM PHUONG Aix Marseille University, CNRS, CINaM-UMR 7325, F-13288 Marseille, France and Hong Duc University, 565 Quang Trung St., Thanh Hoa City, Vietnam NGUYEN MANH AN Hong Duc University, 565 Quang Trung St., Thanh Hoa City, Vietnam E-mail: Received 25 September 2013 Accepted for publication 22 October 2013 Abstract. We report on successful growth of epitaxial high Curie-temperature Ge1−x Mnx quantum dots on Si (001) substrates using the self-assembled approach. By decreasing the growth temperature down to 400 ˚C, we show that the Mn diffusion into the Si substrate can be neglected. No indication of secondary phases or clusters was observed. Ge1−x Mnx quantum dots were found to be epitaxial and perfectly coherent to the Si substrate. We also evidence that the ferromagnetic ordering in Ge1−x Mnx quantum dots persists up to a temperature higher 320 K. It is believed that single-crystalline quantum dots exhibiting a high Curie temperature are potential candidates for the realization of nanoscale spintronic devices. Keywords: ferromagnetic quantum dots, self-assembly, high Curie temperature, spintronics, Stranski-Krastanov growth. I. INTRODUCTION As the device miniaturization reaches technological and physical limits, adding the spin degree of freedom to the electron into conventional electronics appears as a promising solution for the development of a new generation of devices [1]. The development of such spin-based devices requires an efficient injection of spin-polarized currents from ferromagnetic materials into conventional semiconductors. Research dealing with group-IV semiconductors, such as silicon and germanium, represents a particular interest since it allows integrating spintronic devices into the existing Si technology. Germanium, thanks to its small band gap and its high mobility, is .