Investigation of opto-electronic properties on gradient-porosity porous silicon layer

Electrochemical etching with step-gradient current was applied to form gradient-porosity porous silicon (PS) layer on n-Si substrate and Al/gradient-porosity. PS/n-Si structure was fabricated to extract its opto-electronic properties using reflectivity, spectral response, and scanning electron micro...

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Bibliographic Details
Published in:Thin solid films 2011-01, Vol.519 (7), p.2313-2316
Main Authors: Hwang, J.D., Hwang, S.B., Chou, C.H., Chen, Y.H.
Format: Article
Language:English
Subjects:
Aluminum
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Electrical properties
electrochemical etching
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Etching
Exact sciences and technology
gradient-porosity
Optical properties
Physics
Polystyrene resins
Porous silicon
Reflectivity
spectral response
Structure and morphology
thickness
Surface and interface electron states
Surface chemistry
Surfaces and interfaces
thin films and whiskers (structure and nonelectronic properties)
Thin film structure and morphology
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Summary:Electrochemical etching with step-gradient current was applied to form gradient-porosity porous silicon (PS) layer on n-Si substrate and Al/gradient-porosity. PS/n-Si structure was fabricated to extract its opto-electronic properties using reflectivity, spectral response, and scanning electron microscopy. A conventional single-layer PS etched with constant-current was also compared. Compared to the single-layer PS, the absorption wavelength of gradient-porosity PS is blue-shifted due to a smaller quantum size, hence a wider band-gap. Such a wider band-gap leads to a larger barrier-height in Al/gradient-porosity PS than that in Al/single-layer PS one. More dangling bonds are found on the surface of gradient-porosity PS owing to inhomogeneous etching, thus a poor electronic property, though it has a lower broadband antireflection than single-layer PS.
ISSN:0040-6090
1879-2731
DOI:10.1016/j.tsf.2010.11.041