Variation of various properties of LaF${}_3$ deposited on porous silicon by chemical bath and spin coating techniques

Lanthanum fluoride (LaF${}_3$) is an extensively used material for sensors, optical, and electronic devices. Generally, different sophisticated and expensive techniques have been used for the deposition of LaF${}_3$ film to make heterostructured devices that hinders its mass production. The structural, compositional, and electrical properties of LaF${}_3$ heavily depend on the deposition techniques. This report presents an investigation of the variation of the structural or morphological, compositional, and electrical properties of LaF${}_3$ caused by two very low-cost deposition techniques, called chemical bath and spin-coating, on porous silicon (PS) substrate. In both deposition techniques, LaF${}_3$ was synthesized by reacting LaCl${}_3$ with hydrofluoric (HF) acid directly on the PS surface. The morphological and compositional properties of deposited LaF${}_3$ films were investigated by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis, respectively. The spin coated LaF${}_3$ contains less lanthanum, fluorine, and oxygen than chemical bath deposited LaF${}_3$. The current-voltage (I-V) and capacitance-voltage (C-V) characterization confirmed the insulating or dielectric nature of the deposited LaF${}_3$ in the Ag/LaF${}_3$/PS/Ag structure. I-V and C-V characteristics also revealed the production of more leakage current and less capacitance by the spin-coated LaF${}_3$/PS structure than the chemical bath-deposited LaF${}_3$/PS structure. The experimental results indicate that both spin coating and CBD techniques can deposit LaF${}_3$ into the pores of PS for passivation of PS. These simple techniques of passivation of PS may enable the PS to be an important material for electronic device fabrication.