Resonant tunneling diodes (RTDs) composed of a heterostructure of fluoride materials on Si substrates were fabricated. In the fabrication process, Ca{sub}xMg{sub}(1-x)F{sub}2 alloy, rather than conventional CaF{sub}2, was employed as the initial growth layer on the substrate. The Ca{sub}xMg{sub}(1-x)F{sub}2 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 CaF{sub}2 initial layers. As a result of these good properties, the leakage current was considerably reduced in the Ca{sub}xMg{sub}(1-x)F{sub}2 layer. RTDs containing the Ca{sub}xMg{sub}(1-x)F{sub}2 alloy buffer layer exhibited good current-voltage characteristics of negative differential resistance and exhibited improved yield and stability compared to those containing the conventional CaF{sub}2 buffer layer.
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