Nano-Columnar Pore Formation in the Photo-Electrochemical Etching of n-Type 6H SiC

2007 ◽  
Vol 556-557 ◽  
pp. 741-744 ◽  
Author(s):  
Yue Ke ◽  
Robert P. Devaty ◽  
Wolfgang J. Choyke
Keyword(s):  
Growth Mechanism ◽  
Pore Formation ◽  
Electrochemical Etching ◽  
Constant Voltage ◽  
Sem Images ◽  
Etching Condition ◽  
20 Nm ◽  
Porous Sic

We have fabricated columnar nano-porous SiC by photo-electrochemical etching on the C-face of n-type 6H SiC at constant voltage. SEM images reveal that the pores are long, straight and parallel with diameters of about 20 nm. We have produced such layers up to 250 μm thick. The pore morphologies for both Si and C-face SiC samples are compared and discussed as a part of the effort to understand the growth mechanism. It is found that the constant voltage etching condition on C-face SiC is crucial for this nano-columnar pore formation.

Novel Use of Columnar Porous Silicon Carbide Structures as Nanoimprint Lithography Stamps

2008 ◽  
Vol 600-603 ◽  
pp. 871-874 ◽  
Author(s):  
J.H. Leach ◽  
Hadis Morkoç ◽  
Yue Ke ◽  
Robert P. Devaty ◽  
Wolfgang J. Choyke
Keyword(s):  
Nanoimprint Lithography ◽  
Elevated Temperatures ◽  
Electrochemical Etching ◽  
Nanowire Growth ◽  
Porous Si ◽  
Vapor Liquid Solid ◽  
Superior Mechanical Properties ◽  
20 Nm ◽  
Porous Sic ◽  
Solid Type

Columnar porous Si-face 6H-SiC substrates were prepared by a photo-electrochemical etching method and applied as nanoimprint lithography (NIL) stamps. The diameter of the pores in the porous region was about 20 nm and the center-to-center separation between pores was about 60 nm. The columnar porous SiC substrates were subjected to a vapor phase silanization treatment whereby a monolayer of perfluorooctyltrichlorosilane (FOTS) was deposited in order to keep the stamps from sticking to the substrates during the imprint step. Subsequently, the porous SiC stamps were used to imprint polymethylmethacrylate (PMMA) at elevated temperatures and pressures. The imprinted PMMA could then be used to transfer the nanopattern on the columnar porous SiC to other substrates for various purposes; e.g. templates for GaN regrowth, catalysts for nanowire growth by vapor-liquid-solid type methods (VLS), etc. SiC is not typically used for NIL stamps since etch processing of SiC is less mature than that of Si. However, as demonstrated here, there is no reason why SiC cannot be used as a material for NIL stamps. The superior mechanical properties to Si make the use of SiC alluring as a master template for NIL processing.

Structural, Surface Morphological and Photoluminescence Properties of Nanostructured Porous Silicon Material for Optoelectronics Application

2012 ◽  
Vol 584 ◽  
pp. 290-294 ◽  
Author(s):  
Jeyaprakash Pandiarajan ◽  
Natarajan Jeyakumaran ◽  
Natarajan Prithivikumaran
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Light Emission ◽  
Electrochemical Etching ◽  
Light Emitting Diode ◽  
Radiative Transition ◽  
Sem Images ◽  
Optoelectronic Application ◽  
Gap Opening ◽  
P Type

The promotion of silicon (Si) from being the key material for microelectronics to an interesting material for optoelectronic application is a consequence of the possibility to reduce its device dimensionally by a cheap and easy technique. In fact, electrochemical etching of Si under controlled conditions leads to the formation of nanocrystalline porous silicon (PS) where quantum confinement of photo excited carriers and surface species yield to a band gap opening and an increased radiative transition rate resulting in efficient light emission. In the present study, the nanostructured PS samples were prepared using anodic etching of p-type silicon. The effect of current density on structural and optical properties of PS, has been investigated. XRD studies confirm the presence of silicon nanocrystallites in the PS structure. By increasing the current density, the average estimated values of grain size are found to be decreased. SEM images indicate that the pores are surrounded by a thick columnar network of silicon walls. The observed PL spectra at room temperature for all the current densities confirm the formation of PS structures with nanocrystalline features. PL studies reveal that there is a prominent visible emission peak at 606 nm. The obtained variation of intensity in PL emission may be used for intensity varied light emitting diode applications. These studies confirm that the PS is a versatile material with potential for optoelectronics application.

A Short Synopsis of the Current Status of Porous SiC and GaN

2005 ◽  
Vol 483-485 ◽  
pp. 251-256 ◽  
Author(s):  
Y. Shishkin ◽  
Yue Ke ◽  
Robert P. Devaty ◽  
Wolfgang J. Choyke
Keyword(s):  
Historical Development ◽  
Current Status ◽  
Future Prospects ◽  
Sem Images ◽  
Porous Sic

A brief historical development of porous SiC and GaN is given. SEM images of nine porous morphologies in 4H, 6H and 3C SiC are shown along with anodization details. Similarly, two porous GaN morphologies are presented. Applications and future prospects are discussed.

In Situ Observation of an Electrochemical Etching Reaction in Silicon

1995 ◽  
Vol 404 ◽  
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Pore Formation ◽  
Electrochemical Etching ◽  
Ex Situ ◽  
In Situ Observation ◽  
Specimen Holder

AbstractWe describe a TEM specimen holder which has been designed and constructed in order to observe the process of electrochemical pore formation in silicon. The holder incorporates electrical feedthroughs and a sealed reservoir for the electrolyte and it accepts lithographically patterned silicon specimens. We present ex situ observations of progressive pore propagation and show dynamic, in situ observations of electrolyte movement within the pores.

Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ Particles: Polyol-Mediated Synthesis and Luminescent Properties

2007 ◽  
Vol 7 (2) ◽  
pp. 602-609 ◽  
Author(s):  
Zhenling Wang ◽  
Guangzhi Li ◽  
Zewei Quan ◽  
Deyan Kong ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Blue Emission ◽  
Luminescent Properties ◽  
Spherical Particles ◽  
Sem Images ◽  
Blue Emission Band ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
20 Nm

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Pb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodoluminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10–20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb3+-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4–7FJ (J = 6 – 3) transitions due to an energy transfer from WO42− groups to Pb3+.

Fabrication of NiO Nanorings by Bubble-Bursting Bubbles as Templates

2013 ◽  
Vol 464 ◽  
pp. 54-57
Author(s):  
Yun Feng Guo ◽  
Zhi Hua Feng ◽  
Zhi Hao Yuan
Keyword(s):  
Growth Mechanism ◽  
Wall Thickness ◽  
Low Cost ◽  
Heat Treating ◽  
Wire Diameter ◽  
Bubble Bursting ◽  
Inner Diameter ◽  
Average Wall Thickness ◽  
20 Nm

A simple and low-cost method based on a heat-treating of Ni (NO3)2/SiO2film has been developed for fabricating NiO nanorings. The as-prepared nanorings have an inner diameter of 150-250nm and an average wall thickness (namely wire diameter) of approximately 20 nm on the surface of SiO2matrix. Furthermore, a growth mechanism, namely bubble-bursting bubbles as templates was tentatively proposed for understanding the formation of the NiO nanorings.

A Decisive Role of Si and Ge Energy Levels in the Process of Pore Formation during Electrochemical Etching in Hydrofluoric Acid Solutions

2020 ◽  
Vol 495 (1) ◽  
pp. 178-181
Author(s):  
A. M. Khort ◽  
A. G. Yakovenko ◽  
A. A. Dementeva ◽  
Yu. V. Syrov ◽  
A. S. Sigov
Keyword(s):  
Hydrofluoric Acid ◽  
Pore Formation ◽  
Electrochemical Etching ◽  
Energy Levels ◽  
Decisive Role ◽  
Acid Solutions

Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ Particles: Polyol-Mediated Synthesis and Luminescent Properties

2007 ◽  
Vol 7 (2) ◽  
pp. 602-609 ◽  
Author(s):  
Zhenling Wang ◽  
Guangzhi Li ◽  
Zewei Quan ◽  
Deyan Kong ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Blue Emission ◽  
Luminescent Properties ◽  
Spherical Particles ◽  
Sem Images ◽  
Blue Emission Band ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
20 Nm

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Pb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodoluminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10–20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb3+-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4–7FJ (J = 6 – 3) transitions due to an energy transfer from WO42− groups to Pb3+.

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