Magnetic Ge:Mn nanocrystals grown by MBE on insulator substrate for solar cell and photodetector applications

Abstract

In this work, we successfully grew novel dilute magnetic Ge:Mn nanocrystals (Ge:Mn NCs) on SiO2 thin film for metal-oxidesemiconductor (MOS) solar cell and photodetector applications. The innovative Ge:Mn NCs have been grown via solid-state dewetting of ultra-pure thin amorphous Ge:Mn nanolayer deposited by high precision molecular beam epitaxy (MBE) on thin SiO2/Si film. The morphological and structural properties of the Ge:Mn NCs have been determined by atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HR-TEM). The results indicate the formation of homogeneous Ge:Mn NCs on SiO2 with a well-defined spherical shape and small size (∼8 nm). The incorporation of Mn element into Ge matrix has been confirmed by scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX). The magnetic properties of the Ge:Mn NCs have been determined by the superconducting quantum interference device (SQUID). The results show that the Ge:Mn NCs are ferromagnetic and having a Curie temperature above room temperature (∼310 K). The electrical transport and the photocurrent generation in the novel Ge:Mn NCs embedded in the SiO2 film of MOS structure are studied by I-V and photocurrent spectroscopies. The results show that when the Ge:Mn NCs are inserted as an active layer in a SiO2 film of MOS structure, the photocurrent of the MOS structure increase 10 times higher than the dark current.The excellent structural, magnetic and optoelectric properties results indicate that the novel Ge:Mn NCs grown on insulator (SiO2) thin-film via solid-state dewetting can be integrated with spintronic and optoelectronic technologies to produce novel high-performance devices fully compatible with complementary oxide metal (CMOS) technology.