Investigation on Lanthanum Fluoride insulating layer embedding silicon nanocrystals for metal-insulator-semiconductor (MIS) devices

This article reports the investigation on Lanthanum Fluoride (LaF₃) layer embedding silicon nanocrystals (Si-NCs) fabricated using a novel chemical method. Colloidal solution of Si-NCs in hydrofluoric acid (HF) was prepared from meso-porous silicon by ultrasonic vibration (sonication). On a silicon (Si) substrate LaCl₃ is allowed to react with the HF of the prepared Si-NCs colloidal solution at room temperature that resulted LaF₃ crystal deposits as layer on Si containing Si-NCs. The X-Ray diffraction of the deposited layer shows a polycrystalline LaF₃ deposition on silicon. The presence of Si-NCs was observed by SEM. FTIR spectroscopy of the deposited LaF₃ powder also confirmed the presence of Si-NCs. A non-stoichiometric LaF₃ layer embedding Si-NCs was found by EDX analysis. The size of Si-NCs was found to be inversely proportional to the ultrasonic power. Various sizes of the Si crystals were formed during sonication, but the minimum size was found to be of the order of 50 nm.