Schottky-barrier fluctuations in Pb1-xSnxSe infrared sensors

Epitaxial Pb1-xSnxSe layers have been grown on Si substrates, and Schottky-barrier infrared sensors were fabricated in the layers using Pb blocking contacts, The observed current-voltage characteristics (saturation currents j(0) and ideality factors n) as a function of temperature are quantitatively explained with a fluctuation model of the barrier heights [J. H. Werner, W. Guttler, J. Appl. Phys. 69, 1991 (1522)]. The amount of the mean barrier fluctuation sigma, which is typically 10-30 meV. depends on the layer quality and fabrication procedure. Higher sigma causes higher j(0) with increasing saturation values at low temperatures. In addition, the fluctuations cause high n(>2) values at low temperatures. Layers with improved structural quality (higher mobilities and lower threading dislocation densities) lead to lower barrier fluctuations and, therefore, to increased sensitivities. (C) 1996 American Institute of Physics.