Open AccessFeatures of water vapor adsorption and desorption on the surface of non-stoichiometric tin dioxide films
Author(s) -
Dzmitry Adamchuk,
В. К. Ксеневич,
Н. А. Поклонский,
А. И. Ковалев
Publication year - 2020
Publication title -
vescì nacyânalʹnaj akadèmìì navuk belarusì. seryâ fìzìka-matèmatyčnyh navuk
Language(s) - English
Resource type - Journals
eISSN - 2524-2415
pISSN - 1561-2430
DOI - 10.29235/1561-2430-2020-56-1-102-113
Subject(s) - desorption , water vapor , nanocrystalline material , adsorption , relative humidity , tin dioxide , electrical resistivity and conductivity , annealing (glass) , analytical chemistry (journal) , oxygen , thin film , materials science , argon , sputtering , sputter deposition , humidity , chemical vapor deposition , chemistry , nanotechnology , environmental chemistry , metallurgy , organic chemistry , physics , engineering , electrical engineering , thermodynamics
Herein, the influence of water vapor adsorption and desorption processes on the surface of SnO 2− δ nanocrystalline films with different concentrations of oxygen vacancies on their electrical conductivity at room temperature was studied. SnO 2− δ films were synthesized by means of reactive magnetron sputtering of tin in an argon-oxygen plasma followed by 2-stage oxidative annealing. The concentration of oxygen vacancies in the films was varied by changing the 2nd stage annealing temperature within the range 350–400 °C. It was found that in the films with the highest concentration of oxygen vacancies (~10 20 cm −3 ) in the region of low relative humidity (less than ~30 %), an increase in electrical conductivity was observed due to the dissociative adsorption of water molecules with the formation of hydroxyl groups. The adsorption of water vapor on the surface of SnO 2− δ films at room temperature at relative humidity values higher than ~30 % was found to induce a decrease in the electrical conductivity of the samples. The generation of positive and negative EMF pulses between the open surface of SnO 2− δ nanocrystalline films and the one covered by waterproof materials under the adsorption and desorption of water vapor, respectively, was detected. The change of resistance and the generated EMF value under the adsorption-desorption processes was found to increase with the concentration of free charge carriers in the films.