Supersensitive, ultrafast, and broad-band light-harvesting scheme employing carbon nanotube/TiO2 core-shell nanowire geometry.

We demonstrate a novel, feasible strategy for practical application of one-dimensional photodetectors by integrating a carbon nanotube and TiO(2) in a core-shell fashion for breaking the compromise between the photogain and the response/recovery speed. Radial Schottky barriers between carbon nanotube cores and TiO(2) shells and surface states at TiO(2) shell surface regulate electron transport and also facilitate the separation of photogenerated electrons and holes, leading to ultrahigh photogain (G = 1.4 × 10(4)) and the ultrashort response/recovery times (4.3/10.2 ms). Additionally, radial Schottky junction and defect band absorption broaden the detection range (UV-visible). The concept using metallic core oxide-shell geometry with radial Schottky barriers holds potential to pave a new way to realize nanostructured photodetectors for practical use.

[1]  Michael Grätzel,et al.  Photoelectrochemical cells , 2001, Nature.

[2]  Jinyao Tang,et al.  Solution-processed core-shell nanowires for efficient photovoltaic cells. , 2011, Nature nanotechnology.

[3]  Yong Ding,et al.  Photoconductive enhancement of single ZnO nanowire through localized Schottky effects. , 2010, Optics express.

[4]  Hung-Chih Chang,et al.  Significant efficiency enhancement of hybrid solar cells using core-shell nanowire geometry for energy harvesting. , 2011, ACS nano.

[5]  C. C. Kuo,et al.  Photoconductivity in single AlN nanowires by subband gap excitation , 2010 .

[6]  Charles M. Lieber,et al.  Coaxial silicon nanowires as solar cells and nanoelectronic power sources , 2007, Nature.

[7]  Pengyu Fan,et al.  Resonant germanium nanoantenna photodetectors. , 2010, Nano letters.

[8]  Zhiyong Fan,et al.  Photoluminescence and polarized photodetection of single ZnO nanowires , 2004 .

[9]  Jr-Hau He,et al.  Antireflection effect of ZnO nanorod arrays , 2010 .

[10]  Jr-hau He,et al.  Photocarrier Relaxation Behavior of a Single ZnO Nanowire UV Photodetector: Effect of Surface Band Bending , 2012, IEEE Electron Device Letters.

[11]  Jr-Hau He,et al.  Nanowire arrays with controlled structure profiles for maximizing optical collection efficiency , 2011 .

[12]  Tianyou Zhai,et al.  Ultrahigh‐Performance Solar‐Blind Photodetectors Based on Individual Single‐crystalline In2Ge2O7 Nanobelts , 2010, Advanced materials.

[13]  Zhong Lin Wang,et al.  Gigantic enhancement in response and reset time of ZnO UV nanosensor by utilizing Schottky contact and surface functionalization. , 2009, Applied physics letters.

[14]  Igor L. Medintz,et al.  Quantum dot bioconjugates for imaging, labelling and sensing , 2005, Nature materials.

[15]  A. Rao,et al.  Continuous production of aligned carbon nanotubes: a step closer to commercial realization , 1999 .

[16]  Jr-hau He,et al.  Enhanced Recovery Speed of Nanostructured ZnO Photodetectors Using Nanobelt Networks , 2012, IEEE Journal of Selected Topics in Quantum Electronics.

[17]  Y. Bando,et al.  Recent Developments in One‐Dimensional Inorganic Nanostructures for Photodetectors , 2010 .

[18]  X. Li,et al.  Water‐Assisted Growth of Aligned Carbon Nanotube–ZnO Heterojunction Arrays , 2006 .

[19]  P. Hoffmann,et al.  Titanium Dioxide Thin-Film Deposition on Polymer Substrate by Light Induced Chemical Vapor Deposition , 2004 .

[20]  Zhongfan Liu,et al.  Tunable hybrid photodetectors with superhigh responsivity. , 2009, Small.

[21]  X. Bai,et al.  Photoconducting response on bending of individual ZnO nanowires , 2009 .

[22]  Peidong Yang,et al.  Silicon Vertically Integrated Nanowire Field Effect Transistors , 2006 .

[23]  T. Murphy,et al.  Sub-bandgap photoconductivity in ZnO epilayers and extraction of trap density spectra , 2006 .

[24]  Nathan S. Lewis,et al.  Comparison of the device physics principles of planar and radial p-n junction nanorod solar cells , 2005 .

[25]  Y. G. Wang,et al.  Adsorption and desorption of oxygen probed from ZnO nanowire films by photocurrent measurements , 2005 .

[26]  L. Chou,et al.  RuO2 Nanowires and RuO2/TiO2 Core/Shell Nanowires: From Synthesis to Mechanical, Optical, Electrical, and Photoconductive Properties , 2007 .

[27]  Linyou Cao,et al.  Engineering light absorption in semiconductor nanowire devices. , 2009, Nature materials.

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

[29]  W. Sigmund,et al.  Photocatalytic Carbon‐Nanotube–TiO2 Composites , 2009 .

[30]  Hiroshi Harima,et al.  Influence of TiO2/electrode interface on electron transport properties in back contact dye-sensitized solar cells , 2009 .

[31]  S. Ray,et al.  Enhanced broadband photoresponse of Ge/CdS nanowire radial heterostructures , 2009 .

[32]  W. Hsu,et al.  Photocurrent Amplification at Carbon Nanotube–Metal Contacts , 2006 .

[33]  K. Ng,et al.  The Physics of Semiconductor Devices , 2019, Springer Proceedings in Physics.

[34]  A. Kittel,et al.  Persistent photoconductivity in highly porous ZnO films , 2007 .

[35]  P. Avouris,et al.  Photoconductivity of Single Carbon Nanotubes , 2003 .

[36]  Sheng-Yi Lu,et al.  TiO2-coated carbon nanotubes: A redshift enhanced photocatalysis at visible light , 2010 .

[37]  A. Mieszawska,et al.  The synthesis and fabrication of one-dimensional nanoscale heterojunctions. , 2007, Small.

[38]  N. Marzari,et al.  Ultraviolet Photodetectors Based on Anodic TiO2 Nanotube Arrays , 2010 .

[39]  Meng-Yen Tsai,et al.  ZnO‐Coated Carbon Nanotubes: Flexible Piezoelectric Generators , 2011, Advanced materials.

[40]  Shoushan Fan,et al.  Measuring the work function of carbon nanotubes with thermionic method. , 2008, Nano letters.

[41]  Y. Tseng,et al.  Direct probe of heterojunction effects upon photoconductive properties of TiO2 nanotubes fabricated by atomic layer deposition , 2010, Nanotechnology.

[42]  Yulin Deng,et al.  Giant enhancement in UV response of ZnO nanobelts by polymer surface-functionalization. , 2007, Journal of the American Chemical Society.

[43]  Charles M. Lieber,et al.  Growth of nanowire superlattice structures for nanoscale photonics and electronics , 2002, Nature.

[44]  Alberto Piqué,et al.  Laser-sintered mesoporous TiO2 electrodes for dye-sensitized solar cells , 2006 .

[45]  Hung-Chih Chang,et al.  Photon management with core-shell nanowire structures. , 2012, Optics express.

[46]  Gyu-Tae Kim,et al.  Photocurrent in ZnO nanowires grown from Au electrodes , 2004 .

[47]  P. Bhattacharya,et al.  Semiconductor Optoelectronic Devices , 1993 .

[48]  M. Grätzel.  Photoelectrochemical cells : Materials for clean energy , 2001 .

[49]  Jr-hau He,et al.  Surface effects on optical and electrical properties of ZnO nanostructures , 2010 .