A metal foil having a surface roughened by etching, which is made of an alloy
having
an earth-acid metal, preferably niobium, as a main component. A capacitor having
a pair of electrodes and a dielectric material interposed between said pair of
electrodes, wherein at least one of the electrodes is made of the above-mentioned
metal foil, exhibits good high-frequency characteristics, and can be a small-size
capacitor having a large capacitance.
