Hydrogen-sensitive breakdown voltage in the I– V characteristics of tin dioxide-based semiconductors

Abstract

Current ( I)-voltage ( V) characteristics of porous SnO 2-based specimens have been investigated in air as well as in 1.0% H 2 balanced with air in the temperature range from room temperature to 700°C. Pure SnO 2 specimens exhibited non-linear I– V characteristics and breakdown-voltage shift to a low electric field upon exposure to 1.0% H 2 at 300–500°C. Addition of 1.0 mol% Bi 2O 3 to pure SnO 2 was effective for enhancing the breakdown-voltage shift, i.e., H 2 sensitivity. However, further addition of 1.0 mol% Sb 2O 3 or simultaneous addition of 1.0 mol% Sb 2O 3 and 1.0 mol% Cr 2O 3 resulted in a decrease both in the breakdown voltage in air and in the H 2 sensitivity. In every system, adoption of precalcination of raw materials resulted in a decrease in grain size of SnO 2, leading to higher breakdown voltage in air and higher H 2 sensitivity on the whole, being accompanied by improvement in the reproducibility. Tin dioxide specimens loaded with a small amount of Au, Pt, or Pd also exhibited non-linear I– V characteristics and increased non-linearity. However, the noble metal loading was not effective for enhancing the H 2 sensitivity: almost unchanged in the case of Au, but decreased in the cases of Pt and Pd.