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Light Enhanced Electron Transduction and Amplified Sensing at a Nanostructure Modified Semiconductor Interface
Author(s) -
Laminack William I.,
Gole James L.
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201301250
Subject(s) - materials science , nanostructure , semiconductor , photocatalysis , electron , nanotechnology , visible spectrum , optoelectronics , chemistry , physics , biochemistry , quantum mechanics , catalysis
Visible and UV light are demonstrated to significantly enhance the sensing properties of an n‐type porous silicon (PS) extrinsic semiconductor interface to which TiO 2 and titanium oxynitride (TiO 2‐ x N x ) photocatalytic nanostructures are fractionally deposited. The acid/base chemistry of NH 3 , a moderately strong base, and NO 2 , a moderately strong acid, couples to the majority charge carriers of the doped semiconductor as the strong acid (TiO 2 ) enhances the extraction of electrons from NH 3 , and the more basic TiO 2‐ x N x decreases the efficiency of electron extraction relative to the untreated interface. In contrast, NO 2 and a TiO 2 or TiO 2‐ x N x nanostructure‐decorated PS interface compete for the available electrons leading to a distinct time dependent electron transduction dynamics as a function of TiO 2 and TiO 2‐ x N x concentration. Only small concentrations of TiO 2 and its oxynitride and no self‐assembly are required to enhance the response of the decorated interface. With light intensities of less than a few lumens/cm 2 ‐sterad‐nm, responses are enhanced by up to 150% through interaction with visible (and UV) radiation. These light intensities should be compared to the sun's radiation level, ≈500 lumens/cm 2 ‐sterad‐nm suggesting the possibility of solar pumped sensors. The observed behavior in these systems is largely explained by the recently developed Inverse Hard/Soft Acid/Base (IHSAB) concept.