Crystalline Grains and Electrical Properties of Vacuumevaporated SnO2Thin Films

Abstract

AbstractWe have studied grain growth and electrical properties of polycrystalline tin oxide (SnO2) thin films prepared by vacuum-evaporation with a two-step process: evaporation of tin metal films and then oxidation of these metal films. Surface morphology of the SnO2thin films was observed by atomic force microscopy. The grain size of the SnO2thin films is found to increase with the film thickness and oxidation temperature. Kinetics of the grain growth is discussed in terms of a 3-dimensional diffusion limited process. The diode current-voltage (I-V) characteristic of the SnO2/Si heterojunctions (isotype and anisotype) was measured in the temperature range of 14K-383K. Changes in the diode ideality factor and threshold voltage with temperature are discussed. In addition, we present ambient tunnelling I-V results measured from individual SnO2grains.