Hydrogen-Sensitive Breakdown Voltage In The I-V Characteristics Of Tin Dioxide-based Semiconductors

Partially sintered SnO/sub 2/ elements exhibited nonlinear I-V characteristics, and their breakdown voltage shifted to a low electric field upon exposure to 1.0% H/sub 2/ in air at 400-600/spl deg/C. When Bi/sub 2/O/sub 3/(1.0 mol%) was added to pure SnO/sub 2/, the breakdown voltage in air increased and the H/sub 2/-induced breakdown-voltage shift was enhanced. However, further addition of 1.0 mol% Sb/sub 2/O/sub 3/ and Cr/sub 2/O/sub 3/ resulted in a decrease in the breakdown voltage in air as well as in the H/sub 2/ sensitivity. SnO/sub 2/ elements loaded with a small amount of Au, Pt or Pd also exhibited nonlinear I- V characteristics, but the noble metal addition was not effective in enhancing the H/sub 2/ sensitivity.