Mn-Doped Ge Nanoparticles Grown on SiO2Thin Films by Molecular Beam Epitaxy for Photodetector and Solar Cell Applications

In this work, we propose a novel efficient strategy based on the combination of molecular beam epitaxy deposition and the solid-state dewetting process for the growth and self-assembly of magnetic GeMn nanoparticles on the SiO2 substrate. Morphological and structural investigations of magnetic GeMn nanoparticles carried out by AFM and HR-TEM microcopies show that these nanoparticles are very dense (1012 cm–2), are homogeneous, and have a free-defect single-crystalline Ge-Mn phase. The investigations of the magnetic properties carried out by a superconducting quantum interference device (SQUID) reveal that our magnetic GeMn nanoparticles are ferromagnetic and have a Curie record temperature of 325 K. The electrical characterizations of these GeMn nanoparticles when they are inserted in the insulator layer of a metal–insulator–semiconductor Schottky diode show that the nanoparticles contribute to electrical transport and photo-generation of hole–electron pairs when illuminated by white light, resulting in a significant increase in photocurrent of the order of 10 times. This novel growth strategy, which is compatible with CMOS technology, represents a promising path toward the real incorporation of diluted magnetic GeMn nanostructures in photodetection and photovoltaic technologies.