Dielectric and pyroelectric properties of KNO3 thin-layers

A series of thin monocrystalline KNO₃ layers has been grown from the melt by a special technique. The changes of the dielectric constant, d.c. resistivity, activation energy and pyro-electric current behaviour with the layer thickness and temperature have been investigated. Also, the effect of the a.c. frequency on the dielectric constant is checked in the frequency range 1 to 10 kHz. A sharp drop in dielectric constant could be recorded up to 6 kHz. The layers exhibit essentially the same dielectric and pyroelectric properties as bulk KNO₃ single crystals. The various measured parameters of these layers were found to be thickness-dependent. TheI-V characteristics of the layers (5m thickness) reveal the presence of breakdown voltage at 10.95V. Maximum pyrocurrent was obtained at positive d.c. biasing voltage. Also, the layers show a high pyroelectric coefficient, e.g. for layer thickness 8.9m, = 60C cm^–2 K^–1 at 180° C. The study proved that thin layers of potassium nitrate have good pyroelectric properties and should be useful as pyroelectric thermal detector material.