Mn-Doped Ge Nanoparticles Grown on SiO2 Thin 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.