Chemical Vapor Deposition of Cu 2 O and CuO nanosystems for innovative gas sensors Elisabetta Comini, Giorgio Sberveglieri, INFM-CNR, SENSOR Lab, Department of Chemistry and Physics, Brescia University, Brescia, Italy comini@sensor.ing.unibs.it Davide Barreca, ISTM-CNR and INSTM, Department of Chemistry, Padova University, Padova, Italy; Cinzia Sada, INFM and Physics Department, Padova University, Padova, Italy. Alberto Gasparotto, Chiara Maccato,Eugenio Tondello Department of Chemistry, Padova University and INSTM, Padova, Italy; Abstract— Supported copper oxide nanosystems (Cu x O, x=1,2) were synthesized by Chemical Vapor Deposition (CVD) on Al 2 O 3 substrates. Structural and morphological characterization showed an evolution from polycrystalline Cu 2 O granular films to CuO samples with an entangled quasi 1-D morphology upon increasing the growth temperature from 350 to 550°C. For the first time, CVD copper oxide nanosystems were investigated in the gas sensing of CH 3 COCH 3 and CH 3 CH 2 OH. The analyses revealed appreciable responses even at moderate operating temperatures, with characteristics directly dependent on the system composition and nano-organization. I. INTRODUCTION The p-type multi-functional copper oxides (Cu 2 O and CuO) have been investigated for various applications, from solar energy conversion to photovoltaics, from catalysis to solid state gas sensing. Especially in the latter field, organized nanostructured materials, such as nanorods and nanoribbons, feature unique functional properties [1-3], that are significantly advantageous in order to achieve high analyte sensitivity and a rapid response [4]. Nevertheless, the majority of reports has been focused on the use of n-type semiconductors, while the gas sensing properties of supported nano-organized p-type Cu x O (x=1,2) deserve further studies [3,5]. The aim of the present contribution is to highlight the performances of copper oxide nanosystems obtained by CVD in solid state gas sensors as a function of their chemical composition and nano-organization. II. EXPERIMENTAL A. Deposition details Copper oxide nanodeposits were synthesized by means of a custom-built cold-wall CVD reactor under electronic grade O 2 -based reaction atmospheres, using Cu(hfa) 2 •TMEDA (hfa = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionate, TMEDA = N,N,N’,N’-tetramethylethylenediamine) as Cu precursor for the first time. Basing on previous results [6], the deposition conditions adopted in the present work are summarized in Table I. TABLE I. LIST OF TESTED SAMPLES. Sample code Deposition conditions Cu2O Growth T=350°C O2+H2O CuO Growth T=550°C O2 10 mbar Alumina substrates (3×3 mm 2 ) were used for the preparation of gas sensors. Depositions were performed using a precursor heating temperature of 70°C, with a total O 2 flow rate of 200 sccm (total duration=2 h). For the growth experiments carried out in the presence of H 2 O vapor, a water bath kept at 50°C was connected to the gas-line. The gas lines between the precursor vaporizer and the reaction chamber were maintained at 120°C throughout each deposition in order to prevent undesired precursor condensation phenomena. At the end of each experiment, samples were cooled down to room temperature under flowing O 2 . B. Characterizations Glancing Incidence X-ray Diffraction (XRD) measurements were performed at a constant incidence angle of 0.5° by means of a Bruker D8 Advance diffractometer, equipped with a Göbel mirror and a Cu Kα source powered at 40 kV, 40 mA. The angular accuracy was 0.001° and the 978-1-4244-5335-1/09/$26.00 ©2009 IEEE 111 IEEE SENSORS 2009 Conference