			Home About us Contact

Wet Chemical Etching (wet + chemical_etching)

Distribution by Scientific Domains

Physics and Astronomy	66%
Polymers and Materials Science	33%

Selected Abstracts

Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic Properties

ADVANCED FUNCTIONAL MATERIALS, Issue 18 2010
Yongquan Qu
Abstract Photocatalyst mediated photoelectrochemical processes can make use of the photogenerated electrons and holes onsite for photocatalytic redox reactions, and enable the harness and conversion of solar energy into chemical energy, in analogy to natural photosynthesis. However, the photocatalysts available to date are limited by either poor efficiency in the visible light range or insufficient photoelectrochemical stability. Here, it is shown that a Pt/Si/Ag nanowire heterostructure can be rationally synthesized to integrate a nanoscale metal-semiconductor Schottky diode encased in a protective insulating shell with two exposed metal catalysts. The synthesis of Pt/Si/Ag nanowire diodes involves a scalable process including the formation of silicon nanowire array through wet chemical etching, electrodeposition of platinum and photoreduction of silver. The Pt/Si/Ag diodes exhibit highly efficient photocatalytic activity for a wide range of applications including environmental remediation and solar fuel production in the visible range. In this article, photodegradation of indigo carmine and 4-nitrophenol are used to evaluate the photoactivity of Pt/Si/Ag diodes. The Pt/Si/Ag diodes also show high activity for photoconversion of formic acid into carbon dioxide and hydrogen. [source]

Heterointegration of Pt/Si/Ag Nanowire Photodiodes and Their Photocatalytic Properties

Stamps for Submicrometer Soft Lithography Fabricated by Capillary Force Lithography ,

ADVANCED MATERIALS, Issue 13 2004
M. Bruinink
A convenient, inexpensive technique for fabrication of stamps for submicrometer soft lithography from masters with micrometer-size features is presented. Templates fabricated by capillary-force lithography are robust against replica molding of stamps. The Figure shows the resulting metal structure after employing such a second-generation stamp in microcontact printing of octadecanethiol and subsequent wet chemical etching of the underlying gold. [source]

Top-down processed silicon nanowire transistor arrays for biosensing

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2009
Xuan Thang Vu
Abstract We describe the fabrication, electrical and electrochemical characterization of silicon nanowire arrays, which were processed in a top-down approach using combined nanoimprint lithography and wet chemical etching. We used the top silicon layer as contact line and observed an influence of implantation and subsequent annealing of these lines to the device performance. In addition we found a subthreshold slope dependence on wire size. When operated in a liquid environment, wires can be utilized as pH sensors. We characterized the pH sensitivity in the linear range and in the subthreshold operation regime. As a first proof-of-principle experiment for the later use of the sensors in bioassays, we monitored the buildup of polyelectrolyte multilayers on the wire surface. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Preparation of extended microtunnels in GaN by wet chemical etching

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2007
Hsin-Hsiung Huang
Abstract Extended microtunnels with triangular cross sections are demonstrated in GaN layers on sapphire substrates. The depths of the tunnels can easily reach several hundred micrometers by using wet chemical etching. To obtain this result, patterned growth of specially designed GaN layers is carried out on sapphire substrates with metalorganic chemical vapor deposition and subsequently hydride vapor-phase epitaxy techniques. The prepared samples are then chemically etched in molten potassium hydroxide, and microtunnels with triangularly etched cross sections are formed. The planes of the triangular bevels belong to the {112} family. The etch rate of the tunnel can be as high as 10 ,m/min under proper etching conditions. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Structural and optical properties of ZnSe-based diluted magnetic semiconductor quantum-well wire arrays by wet chemical etching

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2010
Tsutomu Muranaka
Abstract The ZnSe-based mesa structures with well-defined and smooth facets were successfully demonstrated by using molecular beam epitaxy (MBE) and wet chemical etching. The ZnSe structures were found to be bound by (111) and (-1-11) facets along the [-110] direction, and bound by (1-11) and (-111) facets along the [110] direction, respectively. The intensities of the non-polarized PL peaks from the [-110]- and [110]-oriented QWW structures were almost proportional to the unetched region and additional decreases were not observed. The PL peaks from the QWW structures were found to be highly polarized when the polarization angle was aligned parallel to the wire direction. The degrees of the linear polarization were 18% for the [-110]-oriented QWW structure and 26% for the [-110]-oriented QWW structure, respectively. The results of the PL and magneto-PL measurements show no process-induced damage to degrade magneto-optical performance of the DMS structures by using this method. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Defect-selective etching of aluminum nitride single crystals

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 7 2007
M. Bickermann
Abstract We have investigated defect-selective wet chemical etching of freestanding AlN single crystals in a molten NaOH-KOH eutectic at temperatures ranging from 240 °C to 400 °C. On nitrogen polar basal planes, hexagonal pyramids/hillocks exceeding 100 µm in diameter may form within seconds of etching at 240 °C. They sometimes are arranged in lines and clusters, thus we attribute them to defects on the surface, presumably originating in the bulk material. On aluminum polar basal planes, the etch pit density after approx. 2,3 min of total etching time at 350 °C corresponds to the screw dislocation density. Additionally, significantly smaller etch pits were found around annealed indentations, in the vicinity of some bigger etch pits after repeated etching, and sometimes also isolated on the surface area. We attribute these etch pits to threading mixed and edge dislocations. On as-grown rhombohedral and prismatic facets no defect-related etching features were observed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]