Highly sensitive layered ZnO/LiNbO3 SAW device with InOx selective layer for NO2 and H2 gas sensing

Abstract Layered surface acoustic wave (SAW) devices for the monitoring of NO2 and H2 in synthetic air have been fabricated on XZ LiNbO3 with a 1.2 μm ZnO guiding layer. To increase selectivity and sensitivity, InOx layers of thickness 40 and 200 nm were employed. The sensor's performance was analyzed in terms of frequency shift as a function of different gas concentrations. The sensors were tested over a range of operating temperatures between 100 and 273 °C. A large response magnitude with fast response and recovery time was observed. Positive frequency shifts of 91 kHz for 2.125 ppm of NO2 and negative frequency shifts of 319 kHz for 1% of H2 in synthetic air are presented; demonstrating the high sensitivity of the layered SAW structure with the DC sputtered InOx thin film. The surface of the layered SAW structure was studied by atomic force microscopy (AFM) before and after the deposition of the InOx selective layer. The AFM analysis demonstrates that the InOx films deposited on ZnO, the guiding layer, resulted in an increase in surface area due to the highly uniform nanostructured surface morphology of InOx.

[1]  M. Ivanovskaya,et al.  Mechanism of O3 and NO2 detection and selectivity of In2O3 sensors , 2001 .

[2]  H. Fritzsche,et al.  Reversible changes of the optical and electrical properties of amorphous InOx by photoreduction and oxidation , 1994 .

[3]  N. Bârsan,et al.  Grain size control in nanocrystalline In2O3 semiconductor gas sensors , 1997 .

[4]  F. Solzbacher,et al.  Fabrication parameters and NO2 sensitivity of reactively RF-sputtered In2O3 thin films , 2000 .

[5]  Koji Moriya,et al.  Mechanism of sensitivity promotion in CO sensor using indium oxide and cobalt oxide , 2000 .

[6]  Raymond E. Dessy,et al.  Surface acoustic wave probe for chemical analysis. I. Introduction and instrument description , 1979 .

[7]  Wojtek Wlodarski,et al.  Low-temperature InOx thin films for O3 and NO2 gas sensing , 2003, SPIE Microtechnologies.

[8]  V. Cimalla,et al.  The influence of deposition parameters on room temperature ozone sensing properties of InOx films , 2001 .

[9]  Koji Moriya,et al.  Indium oxide-based gas sensor for selective detection of CO , 1996 .

[10]  P. Thilakan,et al.  Oxidation dependent crystallization behaviour of IO and ITO thin films deposited by reactive thermal deposition technique , 1998 .

[11]  Tadashi Takada,et al.  Highly sensitive ozone sensor , 1993 .

[12]  V. Cimalla,et al.  Dependence of the photoreduction and oxidation behavior of indium oxide films on substrate temperature and film thickness , 2001 .

[13]  Wojtek Wlodarski,et al.  Investigation on ozone-sensitive In2O3 thin films , 1999 .

[14]  Marian W. Urbanczyk,et al.  Palladium and phthalocyanine bilayer films for hydrogen detection in a surface acoustic wave sensor system , 2003 .

[15]  N. Bârsan,et al.  In2O3 and MoO3–In2O3 thin film semiconductor sensors: interaction with NO2 and O3 , 1998 .

[16]  Jordi Arbiol,et al.  In2O3 films deposited by spray pyrolysis: gas response to reducing (CO, H2) gases , 2004 .

[17]  U. Weimar,et al.  Sol-gel prepared In 2O 3 thin films , 1997 .

[18]  P. Thilakan,et al.  Studies on the preferred orientation changes and its influenced properties on ITO thin films , 1997 .

[19]  K. Zakrzewska,et al.  Mixed oxides as gas sensors , 2001 .

[20]  George Kiriakidis,et al.  Nanostructured holographic recording utilizing InOx photorefractive thin films , 2003, SPIE Microtechnologies.