SiC/ZnOヘテロ接触のNO_x検知機構

概要

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The nitrogen oxide (NO_x) sensing mechanism of SiC/ZnO heterocontact is investigated by thermogravimetric analysis and temperature programed desorption (TPD) of surface product on ZnO. It is known that the electric current through SiC-ZnO interface decreases by the introduction of NO_x gas with water vapor in at mosphere. However, a pronounced decrease in electric current was observed only when a SiC/ZnO heterocon tact specimen was sufficiently exposed to NO_x with wet air. Since SiC surfaces are chemically inactive , the in teraction between ZnO surface and NO_x+H_2O gas is thought to be responsible for the current decrease at the SiCIZnO interface. TPD chromatogram of ZnO after exposure to NO_xshowed two desorption peaks which were assigned to the desorption of -N0^+ and-O-N=O. When the specimen was sufficiently ex posed to NO_x with wet air, an additional TPD signal and marked weight loss at around 180℃ were observed. From these results, formation of zinc nitrite on the ZnO surface is suggested and it would affect the electron transfer process at the ZnO-SiC interface. In conclusion, formation decomposition cycle of zillcnitrite or other nitrite compounds on the ZnO surface is suggested to be the origin of the reversible resistance variation of SiC/ZnO heterocontact by the introduction of NO_x gas with water vapor.
社団法人日本セラミックス協会の論文
1994-03-01