Properties of high sensitivity ZnO surface acoustic wave sensors on SiO2/(100) Si substrates

Abstract The properties of ZnO/SiO2/Si surface acoustic wave (SAW) Love mode sensors were examined and optimized to achieve high mass sensitivity. SAW devices A and B, were designed and fabricated to operate at resonant frequencies around 0.7 and 1.5 GHz. The ZnO films grown by pulsed laser deposition on SiO2/Si demonstrated c-axis growth and the fabricated devices showed guided shear horizontal surface acoustic wave (or Love mode) propagation. Acoustic phase velocity in the ZnO layer was measured in both devices A and B and theoretical and experimental evaluation of the mass sensitivity showed that the maximum sensitivity is obtained for devices with ZnO guiding layer thicknesses of 340 nm and 160 nm for devices A and B, respectively. The performance of the SAW sensors was validated by measuring the mass of a well-characterized polystyrene–polyacrylic acid diblock copolymer film. For the optimized sensors, maximum mass sensitivity values were as high as 4.309 μm2/pg for device A operating at 0.7477 GHz, and 8.643 μm2/pg for device B operating at 1.5860 GHz. The sensors demonstrated large frequency shifts per applied mass (0.1–4 MHz), excellent linearity, and extended range in the femto-gram region. The large frequency shifts indicated that these sensors have the potential to measure mass two to three orders of magnitude lower in the atto-gram range.

[1]  Mengyan Shen,et al.  Optically pumped lasing of ZnO at room temperature , 1991 .

[2]  Guo-Li Shen,et al.  A Mediator-Free Tyrosinase Biosensor Based on ZnO Sol-Gel Matrix , 2005 .

[3]  Carles Cané,et al.  Optimization of SAW sensors with a structure ZnO–SiO2–Si to detect volatile organic compounds , 2006 .

[4]  H. Koinuma,et al.  Exciton spectra of ZnO epitaxial layers on lattice-matched substrates grown with laser-molecular-beam epitaxy , 2000 .

[5]  Tsung-Lin Tsai,et al.  A piezoelectric SH-leaky SAW biosensor for antibody detection , 2004, IEEE International Workshop on Biomedical Circuits and Systems, 2004..

[6]  Antonio J. Ricco,et al.  Characterization of SH acoustic plate mode liquid sensors , 1989 .

[7]  S. Krishnamoorthy,et al.  Development of high frequency ZnO/SiO2/Si Love mode surface acoustic wave devices , 2006 .

[8]  R. Baer,et al.  STW chemical sensors , 1992, IEEE 1992 Ultrasonics Symposium Proceedings.

[9]  S. Basu,et al.  Improved zinc oxide film for gas sensor applications , 2002 .

[10]  Glen McHale,et al.  Mass sensitivity of acoustic wave devices from group and phase velocity measurements , 2002 .

[11]  R. Lareau,et al.  High quality crystalline ZnO buffer layers on sapphire (001) by pulsed laser deposition for III–V nitrides , 1997 .

[12]  M. Shur,et al.  Guided-wave acousto-optic diffraction in AlxGa1−xN epitaxial layers , 2004 .

[13]  M. Eickhoff,et al.  New Materials for Chemical and Biosensors , 2006 .

[14]  Sivashankar Krishnamoorthy,et al.  Development of High frequency Love Mode Surface Acoustic Wave ZnO/SiO/sub 2//Si Devices , 2005, 2005 International Semiconductor Device Research Symposium.

[15]  M. Kompitsas,et al.  Low–Temperature Hydrogen Sensors Based on Au Nanoclusters and Schottky Contacts on ZnO Films Deposited by Pulsed Laser Deposition on Si and ${\hbox{SiO}}_{2}$ Substrates , 2007, IEEE Sensors Journal.

[16]  Minhua Jiang,et al.  A novel method for improving the performance of ZnO gas sensors , 2006 .

[17]  Michael J. Vellekoop,et al.  A love wave sensor for (bio)chemical sensing in liquids , 1994 .

[18]  G. Harding,et al.  A comparison of protocols for the optimisation of detection of bacteria using a surface acoustic wave (SAW) biosensor. , 2000, Biosensors & bioelectronics.

[19]  Stephanus Buettgenbach,et al.  Temperature-compensated Love mode sensors based on quartz/SiO2 and LiTaO3/SiO2 systems , 2001, SPIE Optics East.

[20]  U. Lee,et al.  Structural and rectifying junction properties of self-assembled ZnO nanoparticles in polystyrene diblock copolymers on [100] Si substrates , 2005 .

[21]  Wojtek Wlodarski,et al.  Numerical calculation of SAW sensitivity: application to ZnO/LiTaO3 transducers , 2004 .

[22]  S. Choopun,et al.  Observation of resonant tunneling action in ZnO/Zn0.8Mg0.2O devices , 2002 .

[23]  G. L. Harding,et al.  A study of Love-wave acoustic sensors , 1996 .

[24]  Glen McHale,et al.  Theoretical mass sensitivity of Love wave and layer guided acoustic plate mode sensors , 2002 .

[25]  G. L. Harding,et al.  A multilayer structure for Love-mode acoustic sensors , 1998 .

[26]  G. Chrousos,et al.  Morphological and binding properties of interleukin-6 on thin ZnO films grown on (100) silicon substrates for biosensor applications. , 2006, Biosensors & bioelectronics.

[27]  Satoshi Fujii,et al.  Diamond-based surface acoustic wave devices , 2003 .