Selective area epitaxy of gallium phosphide-based nanostructures on microsphere lithography-patterned Si wafers for visible light optoelectronics

In this study, we present the selective area plasma-assisted molecular beam epitaxial growth of GaP-based nanoheterostructures (nanostubs), incorporating direct bandgap GaAsP or GaPN segments, on patterned SiO₂/Si(001) wafers. A microsphere optical lithography and anisotropic Si wet-etching techniques were employed for wafer-scale surface patterning through SiO₂ growth mask, allowing to obtain either planar or pyramidal pit nucleation site morphologies. X-ray diffraction reciprocal space mapping and Raman microspectroscopy studies confirm compositional homogeneity of the nanostub arrays. The dilute nitride nanostubs display the narrowest and most intense visible red photoluminescence response at room temperature, which is an order of magnitude higher compared to the GaAsP ones. The formation of the nitrogen sub-band in GaPN alloy was confirmed in the framework of density functional theory, providing insights for interpreting the experimental results. These findings demonstrate the feasibility of the proposed approach for fabricating the ordered arrays of nanoscale visible light emitters on silicon.