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Schottky Diode Based on a Single Carbon–Nanotube–ZnO Hybrid Tetrapod for Selective Sensing Applications
Author(s) -
Postica Vasile,
Schütt Fabian,
Adelung Rainer,
Lupan Oleg
Publication year - 2017
Publication title -
advanced materials interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.671
H-Index - 65
ISSN - 2196-7350
DOI - 10.1002/admi.201700507
Subject(s) - materials science , schottky diode , selectivity , carbon nanotube , schottky barrier , fabrication , diode , operating temperature , microscale chemistry , nanotechnology , adsorption , optoelectronics , chemical engineering , catalysis , chemistry , organic chemistry , medicine , alternative medicine , physics , mathematics education , pathology , mathematics , engineering , thermodynamics
In this work, a general strategy to change the selectivity of individual ZnO tetrapod (ZnO‐T)‐Schottky diode‐based devices by hybridization with carbon nanotubes (CNT) is presented. A microscale Schottky diode based on Pt‐nanocontacts to a single ZnO‐T covered/hybridized with CNT, designated as ZnO‐T−CNT, is fabricated and the temperature‐dependent UV and gas sensing properties are investigated. The gas sensing investigations indicate that due to the presence of CNTs on the surface of the ZnO‐T a higher NH 3 response (factor of ≈90) at room temperature is observed, compared to H 2 gas response (≈14). This effect is attributed to the excellent charge transfer between the CNTs and ZnO‐T as well as NH 3 molecule adsorption on the surface of the CNTs, which can efficiently reduce the Schottky barrier height. By increasing the operating temperature up to 150 °C (starting from 50 °C) the NH 3 response is considerably reduced, leading to an excellent H 2 gas selectivity. In the case of H 2 gas, an increase in temperature up to 150 °C shows a considerably increase in gas response of about 140 (≈10 times). Thus, this device offers the possibility to be used for selective detection of NH 3 and H 2 by only changing the operating temperature. Furthermore, by using the developed strategy/approach other materials can be used for the fabrication of gas sensors with selectivity to other gases.