Fluoride Resonant Tunneling Diodes using Lattice-Matched Buffer Layers on Si Substrates

Resonant tunneling diodes (RTDs) composed of a heterostructure of fluoride materials on Si substrates were fabricated. In the fabrication process, Ca_xMg_1-xF₂ alloy, rather than conventional CaF₂, was employed as the initial growth layer on the substrate. The Ca_xMg_1-xF₂ initial layer functioned both as a buffer layer for heteroepitaxy and as the barrier layer in a resonant tunneling structure for electrons. It was grown pinhole-free and had good uniformity compared to conventional CaF₂ initial layers. As a result of these good properties, the leakage current was considerably reduced in the Ca_xMg_1-xF₂ layer. RTDs containing the Ca_xMg_1-xF₂ alloy buffer layer exhibited good current-voltage characteristics of negative differential resistance and exhibited improved yield and stability compared to those containing the conventional CaF₂ buffer layer