High sensitivity of dry-type nanowire sensors with high-k dielectrics for pH detection via capillary atomic force microscope tip coating technique

Huang-Chung Cheng*, Chun Yu Wu, Po Yen Hsu, Chao Lung Wang, Ta Chuan Liao, You Lin Wu

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Dry-type poly-Si nanowire pH sensors with high-k dielectrics have been demonstrated with the aid of novel focus ion beam engineered capillary atomic force microscopy (C-AFM) tip. By means of this C-AFM tip coating technique, the relatively few testing solutions can be transferred onto the surface of a nanowire, preventing the sensor device from the immersion in the liquid and therefore suppressing the possible leakae current from the testing solution. As compared with the TEOS SiO 2 , the pH sensors comprising A l2 O 3 , TiO 2 , and HfO 2 high-k materials exhibit the better sensitivities due to their enhanced capacitances. The best sensitivity (138.7 nA/pH) and linearity (99.69%) for a HfO 2 dielectric can be ascribed to the higher k value and larger bandgap with respect to the Al2 O 3 and TiO 2 , accordingly. Consequently, the C-AFM tip coating technique incorporating with HfO 2 dielectric suggests the potential for the detection of a minute quantity of biomedicines.

Original languageEnglish
Article number6256693
Pages (from-to)1312-1314
Number of pages3
JournalIEEE Electron Device Letters
Volume33
Issue number9
DOIs
StatePublished - 7 Aug 2012

Keywords

  • High-k dielectrics
  • nanowire
  • pH sensor

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