The Formation of Porous Silicon and its Applications to Dielectric Isolation

1984 ◽  
Vol 33 ◽  
Author(s):  
R. C. Frye
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
High Porosity ◽  
Remarkable Property ◽  
Crystalline Orientation ◽  
Advantages And Disadvantages ◽  
Device Applications ◽  
P Type ◽  
Very High ◽  
Minimal Stress

ABSTRACTPorous silicon is formed by the anodic dissolution of p-type silicon in aqueous hydrofluoric acid. Because of its very high porosity, this material can be rapidly cKidized to form thick (˜10 μn) oxide layers with minimal stress on the underlying silicon wafer. A remarkable property of porous silicon is that preserves the crystalline orientation of the substrate despite removal of more than half of the silicon in the etched region, providing a suitable surface for the growth of epitaxial layers. Several schemes for dielectric isolation have been suggested which take advantage of these unique properties. In this paper, the mechanism of porous silicon formation will be presented and the relative advantages and disadvantages for practical device applications will be discussed.

Photovoltaic Characterization of Trapping in Porous Silicon

1994 ◽  
Vol 358 ◽  
Author(s):  
D. W. Boeringer ◽  
R. Tsu
Keyword(s):  
Porous Silicon ◽  
Photovoltaic Effect ◽  
Light Spot ◽  
Dangling Bond ◽  
Photogenerated Electrons ◽  
Device Applications ◽  
Photovoltaic Characterization ◽  
P Type ◽  
Silicon Based ◽  
Position Sensitive Detectors

ABSTRACTWe report the first observation of the lateral photovoltaic effect in porous silicon. Contacts placed on either side of a porous silicon region develop a voltage up to several millivolts if the sample is asymmetrically illuminated. If the light spot is closer to one contact, the voltage will have one polarity; if it is closer to the other contact, the polarity will be opposite. In the case of n-type, the contact nearest the light spot is positive; for p-type, the contact nearest the light spot is negative In the region between the contacts, the photovoltage varies almost linearly with the position of the light spot, over a distance 4.5 cm across. The origin of our lateral photoeffect may be explained by the trapping of photoexcited carriers by a pair of dangling bond centers in porous silicon. In the case of p-type, the photogenerated electrons are trapped by the dangling bond states while holes diffuse away in the substrate. The situation for n-type is opposite; holes are trapped by the dangling bond states while electrons diffuse away in the substrate. This differs from the conventional lateral photoeffect, which arises under the nonuniform illumination of a junction between two layers of differing conductivities. Hamamatsu sells silicon-based position-sensitive detectors with a resolution down to 0.1 µm. The possibility of using this lateral photoeffect to characterize these dangling bond states in porous silicon as well as several possible device applications will be discussed.

scholarly journals Preserving surface area and porosity during fabrication of silicon aerocrystal particles from anodized wafers

2020 ◽  
Author(s):  
C. J. Storey ◽  
E. Nekovic ◽  
A. Kaplan ◽  
W. Theis ◽  
L. T. Canham
Keyword(s):  
Porous Silicon ◽  
Ball Milling ◽  
Surface Area ◽  
Mechanical Milling ◽  
High Surface ◽  
High Porosity ◽  
Processing Times ◽  
Surface Areas ◽  
Processing Techniques ◽  
Very High

Abstract Porous silicon layers on wafers are commonly converted into particles by mechanical milling or ultrasonic fragmentation. The former technique can rapidly generate large batches of microparticles. The latter technique is commonly used for making nanoparticles but processing times are very long and yields, where reported, are often very low. With both processing techniques, the porosity and surface area of the particles generated are often assumed to be similar to those of the parent film. We demonstrate that this is rarely the case, using air-dried high porosity and supercritically dried aerocrystals as examples. We show that whereas ball milling can more quickly generate much higher yields of particles, it is much more damaging to the nanostructures than ultrasonic fragmentation. The latter technique is particularly promising for silicon aerocrystals since processing times are reduced whilst yields are simultaneously raised with ultrahigh porosity structures. Not only that, but very high surface areas (> 500 m2/g) can be completely preserved with ultrasonic fragmentation.

Electrochemical Formation of Porous Silicon Carbide for Micro-Device Applications

2018 ◽  
Vol 924 ◽  
pp. 943-946
Author(s):  
Gael Gautier ◽  
Thomas Defforge ◽  
Guillaume Gommé ◽  
Damien Valente ◽  
Daniel Alquier
Keyword(s):  
Silicon Carbide ◽  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Chemical Etching ◽  
State Of The Art ◽  
Electrolyte Composition ◽  
Substrate Properties ◽  
Device Applications ◽  
Porous Sic ◽  
Doping Type

Anodization of silicon carbide (SiC) in hydrofluoric acid (HF) solutions is a promising way to etch this material which is very resistant against traditional chemical etching methods. Moreover, it has been shown that several reproducible porous SiC morphologies can be performed varying anodization conditions (current density, electrolyte composition, UV lighting) and/or substrate properties (doping type and level). This paper proposes a state of the art of porous SiC etching in GREMAN and a presentation of the morphologies achievable using anodization in HF based electrolytes.

Microstructure of pores in N+-silicon layers

1987 ◽  
Vol 45 ◽  
pp. 252-253
Author(s):  
V. S. Kaushik
Keyword(s):  
Porous Silicon ◽  
Hydrofluoric Acid ◽  
Silicon Layer ◽  
Porous Silicon Layer ◽  
Silicon On Insulator ◽  
Cross Sectional ◽  
Porous Layers ◽  
Doped Silicon ◽  
Oxidized Porous Silicon ◽  
P Type

Oxidized porous silicon has drawn considerable interest as one of the alternatives for implementing silicon-on-insulator technology. Buried porous layers can be formed by utilizing the preferential pore formation in highly doped silicon during anodic etching in hydrofluoric acid. This porous silicon layer (PSL) can be subsequently oxidized rapidly at low temperatures to yield a device-quality silicon island layer, which is dielectrically isolated from the substrate. Although pores can be formed in both n-type and p-type silicon, the latter has received more attention. This paper presents the results of cross-sectional TEM (XTEM) observations of the microstructure of pores in n+ silicon.Samples used in this study were n- /n+/n- doped silicon (001) wafers which had been anodically etched in a hydrofluoric acid solution to form the PSL in the n+ layer via trenches etched through the n- surface layer.

A novel process for the preparation of thick porous silicon layers with very high porosity

2005 ◽  
Vol 202 (8) ◽  
pp. 1597-1601 ◽  
Author(s):  
A. Feyh ◽  
F. Laermer ◽  
S. Kronmüller ◽  
W. Mokwa
Keyword(s):  
Porous Silicon ◽  
High Porosity ◽  
Very High

scholarly journals Nuclear mass measurements with radioactive ion beams

2019 ◽  
Vol 28 (04) ◽  
pp. 1930005 ◽  
Author(s):  
Michael A. Famiano
Keyword(s):  
Mass Measurement ◽  
Measurement Techniques ◽  
Nuclear Mass ◽  
Mass Measurements ◽  
Future Directions ◽  
Advantages And Disadvantages ◽  
Nuclear Masses ◽  
Under Construction ◽  
Very High ◽  
Practical Constraints

Nuclear masses are the most fundamental of all nuclear properties, yet they can provide a wealth of knowledge, including information on astrophysical sites, constraints on existing theory, and fundamental symmetries. In nearly all applications, it is necessary to measure nuclear masses with very high precision. As mass measurements push to more short-lived and more massive nuclei, the practical constraints on mass measurement techniques become more exacting. Various techniques used to measure nuclear masses, including their advantages and disadvantages are described. Descriptions of some of the world facilities at which the nuclear mass measurements are performed are given, and brief summaries of planned facilities are presented. Future directions are mentioned, and conclusions are presented which provide a possible outlook and emphasis on upcoming plans for nuclear mass measurements at existing facilities, those under construction, and those being planned.

SiC Epitaxial Layers Grown by Sublimation Method and their Electrical Properties

2007 ◽  
Vol 556-557 ◽  
pp. 153-156
Author(s):  
Chi Kwon Park ◽  
Gi Sub Lee ◽  
Ju Young Lee ◽  
Myung Ok Kyun ◽  
Won Jae Lee ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Epitaxial Layer ◽  
Light Emission ◽  
Epitaxial Layers ◽  
Current Voltage ◽  
Space Technique ◽  
Sublimation Method ◽  
Device Applications ◽  
P Type ◽  
Surface Morphologies

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. In this study, we aimed to systematically investigate surface morphologies and electrical properties of SiC epitaxial layers grown with varying a SiC/Al ratio in a SiC source powder during the sublimation growth using the CST method. It was confirmed that the acceptor concentration of epitaxial layer was continuously decreased with increasing the SiC/Al ratio. The blue light emission was successfully observed on a PN diode structure fabricated with the p-type SiC epitaxial layer. Furthermore, 4H-SiC MESFETs having a micron-gate length were fabricated using a lithography process and their current-voltage performances were characterized.

Temperature effect on the roughness of the formation interface of p-type porous silicon

1998 ◽  
Vol 84 (6) ◽  
pp. 3129-3133 ◽  
Author(s):  
S. Setzu ◽  
G. Lérondel ◽  
R. Romestain
Keyword(s):  
Porous Silicon ◽  
Temperature Effect ◽  
P Type

Second Paper: Failure-Survival Automatic Flight Control Systems for Aircraft with Particular Reference to a High Reliability Electrohydraulic Actuator

1965 ◽  
Vol 180 (1) ◽  
pp. 246-259
Author(s):  
R. Ruggles
Keyword(s):  
Control System ◽  
Control Systems ◽  
Flight Control ◽  
High Reliability ◽  
Supply System ◽  
Design Criteria ◽  
Flight Control System ◽  
Advantages And Disadvantages ◽  
System Configurations ◽  
Very High

The author discusses some of the problems of failure-survival automatic flight control systems and suggests some basic ground rules as design criteria. The advantages and disadvantages of some of the main types of system are discussed: duplex, triplex, triple component, duplicate-monitored and quadruplex systems being covered. In particular, a quadruplex actuator is described which has been designed and developed mainly for automatic flight control system applications where a very high degrees of failure-survival capability is required. A detailed failure analysis of the various systems is carried out and the importance of the electrical and hydraulic supply system configurations and failure rates is brought out.

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