Epitaxial deposition of LaF3 thin films on Si using deep eutectic solvent based facile and green chemical route

Abstract

Epitaxial lanthanum fluoride (LaF3) is considered an important and outstanding material for the fabrication of Metal–Insulator–Semiconductor (MIS) capacitive devices. In the quest of finding a green and low-cost scalable technique for the epitaxial deposition of LaF3 thin-film, this article presents an investigation on a home-made deep eutectic solvent (DES)-based chemical route for LaF3 thin film deposition on p-type silicon (p-Si) using the spin coating technique. The x-ray diffraction study confirmed the epitaxial deposition of LaF3 film on the p-Si substrate. An almost pinhole-free homogeneous surface and nearly stoichiometric epitaxial LaF3 were observed on the Si substrate through scanning electron microscopy and energy dispersive x-ray spectroscopy, respectively. From the capacitance–voltage (C–V) characteristics, the capacitance of the Ag/LaF3/p-Si/Ag device with four-layer LaF3 was maximum among the Ag/LaF3/p-Si/Ag devices with two-layer, four-layer, and six-layer LaF3. The flat band potential of the Ag/LaF3/p-Si/Ag structure was determined from the Mott–Schottky plot. The experimental results indicate that the DES-based epitaxial deposition of LaF3 film on the p-Si substrate could be a highly promising technique for the fabrication of LaF3-based MIS capacitive devices.