Dissociative Gas Sensing at Metal Oxide Surfaces

The low- and high-temperature gas sensing behavior of hydrogenated diamond (HD) and metal oxide (MOx) materials is compared and contrasted. We present evidence that at room temperature and above both kinds of materials are coated with a thin surface electrolyte layer in which gas molecules can be adsorbed and in which adsorbed gases may undergo electrolytic dissociation. We show that both kinds of materials respond in a very similar way when exposed to acid and base vapors and that no gas response is observed otherwise. Heating beyond 200degC removes the surface electrolyte layer from both kinds of materials. Whereas at MOx surfaces, the established combustive gas sensing effect sets in, the surface conductivity and the gas sensitivity of HD samples is lost due to the disappearance of the surface transfer doping effect.

[1]  Hong-Ming Lin,et al.  UV enhancement of the gas sensing properties of nano-TiO2 , 2003 .

[2]  Yang Li,et al.  Fast response thin film SnO2 gas sensors operating at room temperature , 2006 .

[3]  M. Stutzmann,et al.  pH sensors based on hydrogenated diamond surfaces , 2005 .

[4]  Yoshiyuki Sakaguchi,et al.  Hydrogenating Effect of Single-Crystal Diamond Surface , 1992 .

[5]  Giorgio Sberveglieri,et al.  RGTO: a new technique for preparing SnO/sub 2/ sputtered thin film as gas sensors , 1991, TRANSDUCERS '91: 1991 International Conference on Solid-State Sensors and Actuators. Digest of Technical Papers.

[6]  I. Eisele,et al.  Light enhanced NO2 gas sensing with tin oxide at room temperature: conductance and work function measurements , 2003 .

[7]  Riedel,et al.  Origin of surface conductivity in diamond , 2000, Physical review letters.

[8]  Theodor Doll,et al.  Adsorbed water as key to room temperature gas-sensitive reactions in work function type sensors: the carbonate–carbon dioxide system , 1999 .

[9]  K. V. Ravi,et al.  Hydrogen passivation of electrically active defects in diamond , 1989 .

[10]  O. Weidemann,et al.  Gas Sensing Interactions at Hydrogenated Diamond Surfaces , 2007, IEEE Sensors Journal.

[11]  Hangsheng Yang,et al.  Mass spectrometric study of low-pressure inductively coupled plasma for chemical vapor deposition of cubic boron nitride films , 2003 .

[12]  R. Gi,et al.  Hall Effect Measurements of Surface Conductive Layer on Undoped Diamond Films in NO2 and NH3 Atmospheres , 1999 .

[13]  Giorgio Sberveglieri,et al.  The kinetics of formation of gas-sensitive RGTO-SnO2 films , 1995 .

[14]  D. E. Yates,et al.  Site-binding model of the electrical double layer at the oxide/water interface , 1974 .

[15]  Giorgio Sberveglieri,et al.  Light enhanced gas sensing properties of indium oxide and tin dioxide sensors , 2000 .

[16]  Shan Gao,et al.  Alcohols and acetone sensing properties of SnO2 thin films deposited by dip-coating , 2006 .

[17]  Masamori Iida,et al.  Formation Mechanism of p-Type Surface Conductive Layer on Deposited Diamond Films , 1995 .

[18]  R. Rowell,et al.  Physical Chemistry of Surfaces, 6th ed. , 1998 .

[19]  Elisabetta Comini,et al.  UV light activation of tin oxide thin films for NO2 sensing at low temperatures , 2001 .

[20]  Hiroshi Kawarada,et al.  Enhancement/Depletion Surface Channel Field Effect Transistors of Diamond and Their Logic Circuits , 1997 .