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
_x
Mg
_1-x
F
₂
alloy, rather than conventional CaF
₂
, was employed as the initial growth layer on the substrate. The Ca
_x
Mg
_1-x
F
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
₂
initial layers. As a result of these good properties, the leakage current was considerably reduced in the Ca
_x
Mg
_1-x
F
₂
layer. RTDs containing the Ca
_x
Mg
_1-x
F
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
₂
buffer layer