SCHOTTKY-BARRIER FLUCTUATIONS IN PB1-XSNXSE INFRARED-SENSORS

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