UV-assisted alcohol sensing using SnO2 functionalized GaN nanowire devices

Abstract A chemiresistor type sensor for selective alcohol sensing has been realized from gallium nitride (GaN) nanowires (NWs) functionalized with sputter-deposited tin dioxide (SnO2) nanoparticles. Two-terminal devices were fabricated using standard microfabrication techniques with the individual NWs air-bridged between the two metal contact pads. Through a combination of X-ray diffraction (XRD), electron-backscatter-diffraction (EBSD), and TEM/STEM techniques, we confirmed the presence of rutile SnO2 nanocrystals on the GaN surface. A change in device current is observed when the device is exposed to alcohol vapors (methanol, ethanol, propanol, and butanol) at room temperature under 215–400 nm UV illumination with 3.75 mW/m2 intensity at 365 nm wavelength. The sensor reproducibly responded to a wide range of alcohol vapor concentrations, from 5000 μmol/mol (ppm) down to 1 μmol/mol (ppm) in air. Notably, the devices show low sensitivity to acetone and hexane, which allows them to selectively detect the primary alcohol vapors mixed with these two common volatile organic compounds (VOCs). The sensor response was not observed without UV excitation. From the experimental results we found a relationship between the response towards the alcohol vapors and the length of carbon chain in the molecule: the chemiresistive response decreases with the increasing carbon chain from methanol to n-butanol. In addition, we observed that the isomeric branching in i-propanol and i-butanol caused reduced response as compared to n-propanol and n-butanol, respectively. We have qualitatively explained the sensor operation by employing a mechanism, which includes oxidation of analyte molecules on the SnO2 surface, leading to enhanced photoconductivity in GaN nanowire.

[1]  Abhishek Motayed,et al.  Highly selective GaN-nanowire/TiO2-nanocluster hybrid sensors for detection of benzene and related environment pollutants , 2011, Nanotechnology.

[2]  Liang Peng,et al.  Light induced enhancing gas sensitivity of copper-doped zinc oxide at room temperature , 2008 .

[3]  Chi-En Lu,et al.  Humidity Sensors: A Review of Materials and Mechanisms , 2005 .

[4]  N. Bârsan,et al.  Metal oxide-based gas sensor research: How to? , 2007 .

[5]  Giorgio Sberveglieri,et al.  Classical and novel techniques for the preparation of SnO2 thin-film gas sensors☆ , 1992 .

[6]  Martin Moskovits,et al.  Nanoengineered chemiresistors: the interplay between electron transport and chemisorption properties of morphologically encoded SnO2 nanowires , 2007 .

[7]  N. Barsan,et al.  Fundamental and practical aspects in the design of nanoscaled SnO2 gas sensors: a status report , 1999 .

[8]  Zhaoxiong Xie,et al.  High-sensitivity humidity sensor based on a single SnO(2) nanowire. , 2007, Journal of the American Chemical Society.

[9]  H. Lüth.  Surfaces and Interfaces of Solid Materials , 2012 .

[10]  J. T. Ranney,et al.  The Surface Science of Metal Oxides , 1995 .

[11]  Giorgio Sberveglieri,et al.  Electrical-Based Gas Sensing , 2009 .

[12]  J. I. Brauman,et al.  Gas-phase acidities of alcohols. Effects of alkyl groups , 1968 .

[13]  U. Diebold,et al.  The surface and materials science of tin oxide , 2005 .

[14]  M. Bowker,et al.  XPS, UPS and thermal desorption studies of alcohol adsorption on Cu(110): I. Methanol , 1980 .

[15]  D. Kohl.  Surface processes in the detection of reducing gases with SnO2-based devices , 1989 .

[16]  Hao Gong,et al.  Interaction between thin-film tin oxide gas sensor and five organic vapors , 1999 .

[17]  Patrick L. Feng,et al.  Achieving fast oxygen response in individual β-Ga2O3 nanowires by ultraviolet illumination , 2006 .

[18]  Norio Miura,et al.  Relationship between ethanol gas sensitivity and surface catalytic property of tin oxide sensors modified with acidic or basic oxides , 2000 .

[19]  Steven M. George,et al.  Steady-state and transient photoconductivity in c-axis GaN nanowires grown by nitrogen-plasma-assisted molecular beam epitaxy , 2010 .

[20]  R. Vispute,et al.  Electrical, thermal, and microstructural characteristics of Ti/Al/Ti/Au multilayer Ohmic contacts to n-type GaN , 2003 .

[21]  Russell Binions,et al.  Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring , 2010, Sensors.

[22]  J. Mackenzie,et al.  Ethanol gas sensing properties of SnO2-based thin-film sensors prepared by the sol-gel process , 1993 .

[23]  F. Bechstedt,et al.  Tin dioxide from first principles: Quasiparticle electronic states and optical properties , 2011 .

[24]  Joachim Goschnick,et al.  A gradient microarray electronic nose based on percolating SnO(2) nanowire sensing elements. , 2007, Nano letters.

[25]  Hao Shen,et al.  Size-dependent photoconductance in SnO2 nanowires. , 2005, Small.

[26]  John B. Shoven,et al.  I , Edinburgh Medical and Surgical Journal.

[27]  I. Tanaka,et al.  Tuning the chemical functionality of a gas sensitive material : Water adsorption on SnO2(101) , 2006 .

[28]  Richard J. Ewen,et al.  Highly sensitive room temperature sensors based on the UV-LED activation of zinc oxide nanoparticles , 2008 .

[29]  S. Fujita,et al.  UV-B Sensor Based on a SnO2 Thin Film , 2009 .

[30]  Martin Moskovits,et al.  Chemical Sensing and Catalysis by One-Dimensional Metal-Oxide Nanostructures , 2004 .

[31]  Joan Ramon Morante,et al.  Influence of the catalytic introduction procedure on the nano-SnO2 gas sensor performances , 2001 .

[32]  Martin Moskovits,et al.  Detection of CO and O2 Using Tin Oxide Nanowire Sensors , 2003 .

[33]  S. Morrison,et al.  Semiconductor gas sensors , 1985 .

[34]  D. Cox,et al.  Oxygen-vacancy-controlled chemistry on a metal oxide surface: methanol dissociation and oxidation on SnO2(110) , 1994 .

[35]  Peidong Yang,et al.  Nanowire ultraviolet photodetectors and optical switches , 2002 .

[36]  J. I. Brauman,et al.  Gas-phase acidities of alcohols , 1970 .

[37]  Yu Wang,et al.  The enhanced alcohol-sensing response of ultrathin WO3 nanoplates , 2010, Nanotechnology.

[38]  M. Bowker,et al.  XPS, UPS and thermal desorption studies of alcohol adsorption on Cu(110): II. Higher alcohols , 1982 .

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

[40]  Shih-Chia Chang.  Oxygen chemisorption on tin oxide: Correlation between electrical conductivity and EPR measurements , 1980 .

[41]  Elson Longo,et al.  A New Method to Control Particle Size and Particle Size Distribution of SnO2 Nanoparticles for Gas Sensor Applications , 2000 .

[42]  Axel Lorke,et al.  Nanostructured gas sensors and electrical characterization of deposited SnO2 nanoparticles in ambient gas atmosphere , 2005 .

[43]  Y. Wen,et al.  Dependence of morphologies for SnO2 nanostructures on their sensing property , 2011 .

[44]  Sanjay Mathur,et al.  Equivalence between thermal and room temperature UV light-modulated responses of gas sensors based on individual SnO2 nanowires , 2009 .

[45]  K. Bertness,et al.  Mechanism for spontaneous growth of GaN nanowires with molecular beam epitaxy , 2008 .

[46]  Peidong Yang,et al.  Photochemical sensing of NO(2) with SnO(2) nanoribbon nanosensors at room temperature. , 2002, Angewandte Chemie.

[47]  Jason L. Johnson,et al.  Room temperature hydrogen detection using Pd-coated GaN nanowires , 2008 .

[48]  C. Soci,et al.  ZnO nanowire UV photodetectors with high internal gain. , 2007, Nano letters.

[49]  K. Bertness,et al.  Nucleation conditions for catalyst-free GaN nanowires , 2007 .

[50]  J. Wu,et al.  Ultraviolet photodetectors made from SnO2 nanowires , 2009 .

[51]  Ian H. Stevenson,et al.  Principles and mechanisms of gas sensing by GaN nanowires functionalized with gold nanoparticles , 2006 .

[52]  Mahiko Nagao,et al.  Relation between the amounts of chemisorbed and physisorbed water on metal oxides , 1969 .

[53]  Thomas Richter,et al.  Size-dependent photoconductivity in MBE-grown GaN-nanowires. , 2005, Nano letters.

[54]  Yang-Kyu Choi,et al.  Chemical sensors based on nanostructured materials , 2007 .