Atomic Layer Etching of Porous Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
I. H. Libon ◽  
C. Voelkmann ◽  
V. Petrova-Koch ◽  
F. Koch
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Lower Energy ◽  
Room Temperature ◽  
Size Dependence ◽  
Atomic Layer ◽  
Layer By Layer ◽  
Energy Limit ◽  
First Time ◽  
Atomic Layer Etching

AbstractIn this work we describe the controlled shifting of the PL peak of p+ (10 mΩcm) porous silicon (PoSi) by means of atomic layer etching (ALEP). We hereby study the cluster-size dependence of the PL of this material. By this technique of repeated oxidation by H2O2 and stripping of the oxidized surface layer, we reduced the size of the crystallites layer by layer. In all previous reports the PoSi PL appeared to have a natural lower energy limit of ≈ 1.4 eV. We report for the first time a continuous shift of the PoSi PL peak between 1.01 and 1.20 eV. This observation allows us to draw conclusions for the luminescence mechanism: it proves that geometrical quantum confinement in Si crystallites is responsible for the efficient room-temperature PL in PoSi near the indirect bandgap of c-Si. Together with observations of size-independent PL peaks around 1.6 eV in thermally oxidized samples this result indicates that the PoSi PL cannot be described by one origin alone. Both the existence of molecular centers and the geometrical quantum confinement are valid in their specific range of etching and post-anodic treatment parameters.

A Novel Layer-By-Layer Hetero-Epitaxy Of Germanium On Silicon (100) Surface

1998 ◽  
Vol 533 ◽  
Author(s):  
S. Sugahara ◽  
M. Matsuyama ◽  
K. Hosaka ◽  
K. Ikeda ◽  
Y. Uchida ◽  
...  
Keyword(s):  
Film Thickness ◽  
Substrate Temperature ◽  
Film Growth ◽  
Atomic Layer ◽  
Temperature Modulation ◽  
Layer By Layer ◽  
Isothermal Conditions ◽  
First Time

AbstractLayer-by-layer hetero-epitaxy of Ge has been successfully demonstrated on the Si(100) surface by combining the initial IML-Ge film growth on the Si surface and the successive Ge atomic-layer-epitxy (ALE), for the first time. The former was achieved using the substrate temperature modulation with alternate exposures of GeCL4 and atomic H, and the later was established by cyclic exposures of (CH 3)2GeH2 and atomic H under isothermal conditions. XPS measurements confirmed a discrete and uniform increase in the grown Ge film thickness with one monolayer/cycle step up to the critical Ge thickness, and no C contamination at the Ge/Si interface. Critical exposure for the saturated Ge adsorption was different from that for the homo-ALE on the bulk Ge surface.

Optical Studies of Electroluminescent Structures from Porous Silicon

1992 ◽  
Vol 283 ◽  
Author(s):  
J. F. Harvey ◽  
R. A. Lux ◽  
D. C. Morton ◽  
G. F. McLane ◽  
R. Tsu
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Light Emitting Diode ◽  
Spectral Peak ◽  
Electrical Excitation ◽  
Silicon Structure ◽  
Electrical Measurements ◽  
Optical Studies ◽  
Light Emitting

ABSTRACTTwo components of the electroluminescence (EL) from porous silicon light emitting diode (LED) devices have been observed. A slower component and a faster component have been identified. The slower component has a spectral peak shifted to the red from the corresponding photoluminescence (PL) spectrum. The faster component has a spectral peak well in the infrared (IR). Optical and electrical measurements of these two components are discussed. The temperature dependence of the two EL components are presented and contrasted. Our measurements demonstrate that the two EL components and the PL result from recombination in different parts of the porous silicon structure. As the temperature is reduced below room temperature the slower EL exhibits a decrease in intensity at relatively high temperatures, suggesting a freeze out of electrical carriers due to quantum confinement, resulting in a much reduced electrical excitation of the EL.

Raman and Optical Characterization of Porous Silicon

1991 ◽  
Vol 256 ◽  
Author(s):  
J. F. Harvey ◽  
H. Shen ◽  
R. A. Lux ◽  
M. Dutita ◽  
J. Pamulapati ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Thermal Dissociation ◽  
Life Time ◽  
High Energy ◽  
Bulk Silicon ◽  
Energy Peak ◽  
Time Changes

ABSTRACTRaman spectra from electrochemically etched porous silicon are correlated with photoluminescence (PL) data from the same spots of the sample. This correlation is consistent with optical properties of quantum confinement. The dielectric constant determined from angle resolved ellipsometry gives values far below that of bulk silicon. This reduction is due to the combined effects of voids as well as quantum confinement. The PL spectrum shows a weak high energy peak around 2.8eV in addition to the strong broad peak at 1.5 to 1.9eV. The temperature dependence of PL resembles that of bound excitons such as Si:S, having a thermal dissociation energy of 100 meV near room temperature. The radiation life time changes from tens of microseconds near room temperature to a few milliseconds at liquid helium temperatures. The rapid increase in lifetime and decrease in PL intensity at low temperatures indicates that phonons are probably involved.

A New Synthesis of BaHPO4 Precipitated by BaCO3-H3PO4-NaOH System at Room Temperature

2013 ◽  
Vol 717 ◽  
pp. 37-43
Author(s):  
Ban Jong Boonchom ◽  
Chesta Ruttanapun ◽  
Montree Thongkam ◽  
Pachernchaipat Chaiyasith ◽  
Somsak Woramongkonchai ◽  
...  
Keyword(s):  
Rapid Method ◽  
Thermodynamic Functions ◽  
Lower Energy ◽  
Room Temperature ◽  
Spontaneous Process ◽  
New Synthesis ◽  
Single Well ◽  
First Time

Barium hydrogenphosphate, BaHPO4 was synthesized for the first time through simple and rapid method using BaCO3-H3PO4-NaOH, pH =9.0 at room temperature for 30 min. The studied BaHPO4 decomposed in a single well-defined stage via deprotonated hydrogenphosphate reactions, revealed by TG/DTG and DSC techniques. The calculated wavenumbers based on DSC peak were comparable with FTIR results, which support the breaking bonds of P-OH (HPO42-) in the deprotonated hydrogenphosphate reactions. The thermodynamic functions (ΔH*, ΔG*, and ΔS*) for the deprotonated hydrogenphosphate reactions calculated from DSC data indicate that the deprotonated HPO42- reaction occur a lower-energy pathway and spontaneous process. The FTIR, XRD and SEM data of the studied BaHPO4 and its decomposed product Ba2P2O7 are also reported.

Can Oxidation and Other Treatments Help Us Understand the Nature of Light-Emitting Porous Silicon?

1993 ◽  
Vol 298 ◽  
Author(s):  
P.M. Fauchet ◽  
E. Ettedgui ◽  
A. Raisanen ◽  
L.J. Brillson ◽  
F. Seiferth ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Quantum Confinement ◽  
Room Temperature ◽  
Vacuum Annealing ◽  
Surface States ◽  
Careful Analysis ◽  
Experimental Results ◽  
Dangling Bonds ◽  
Light Emitting ◽  
Confinement Model

AbstractUsing a careful analysis of the properties of light-emitting porous silicon (LEpSi), we conclude that a version of the “smart” quantum confinement model which was first proposed by F. Koch et al [Mat. Res. Soc. Symp. Proc. 283, 197 (1993)] and allows for the existence of surface states and dangling bonds, is compatible with experimental results. Among the new results we present in support of this model, the most striking ones concern the strong infrared photoluminescence that dominates the room temperature cw spectrum after vacuum annealing above 600 K.

Layer by Layer Etching of the Highly Oriented Pyrolythic Graphite by Using Atomic Layer Etching

2011 ◽  
Vol 158 (12) ◽  
pp. D710 ◽  
Author(s):  
Y. Y. Kim ◽  
W. S. Lim ◽  
J. B. Park ◽  
G. Y. Yeom
Keyword(s):  
Atomic Layer ◽  
Layer By Layer ◽  
Atomic Layer Etching

scholarly journals Cyclic Etch/Passivation-Deposition as an All-Spatial Concept toward High-Rate Room Temperature Atomic Layer Etching

2015 ◽  
Vol 4 (6) ◽  
pp. N5067-N5076 ◽  
Author(s):  
F. Roozeboom ◽  
F. van den Bruele ◽  
Y. Creyghton ◽  
P. Poodt ◽  
W. M. M. Kessels
Keyword(s):  
Room Temperature ◽  
Atomic Layer ◽  
High Rate ◽  
Spatial Concept ◽  
Atomic Layer Etching

Pholuminuksence Studies on Porous Silioon Quantum Confinement Mechanism

1993 ◽  
Vol 298 ◽  
Author(s):  
Shulin Zhang ◽  
Kuoksan He ◽  
Yangtian Hou ◽  
Xin Wang ◽  
Jingjian Li ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Current Density ◽  
Quantum Wire ◽  
Quantum Confinement ◽  
Mechanism Model ◽  
Peak Energy ◽  
P Type ◽  
Silicon Based ◽  
First Time ◽  
Photoluminescence Peak

AbstractA novel step—like and pinning behavior of photoluminescence peak energy connected with changes in the concentration of HIF and current density were for the first time observed for p— type porous silicon. Based on a theoretical calculation of the electron structure of the silicon quantum wire it is argued that these behaviors can be explained in terms of a novel formation mechanism model of porous silicon.

scholarly journals Electro-Quasistatic Animal Body Communication for Untethered Rodent Biopotential Recording

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shreeya Sriram ◽  
Shitij Avlani ◽  
Matthew P. Ward ◽  
Shreyas Sen
Keyword(s):  
Lower Energy ◽  
Sensor Node ◽  
State Of The Art ◽  
The Body ◽  
Animal Body ◽  
Current State ◽  
Communication Modalities ◽  
First Time ◽  
Biopotential Recording

AbstractContinuous multi-channel monitoring of biopotential signals is vital in understanding the body as a whole, facilitating accurate models and predictions in neural research. The current state of the art in wireless technologies for untethered biopotential recordings rely on radiative electromagnetic (EM) fields. In such transmissions, only a small fraction of this energy is received since the EM fields are widely radiated resulting in lossy inefficient systems. Using the body as a communication medium (similar to a ’wire’) allows for the containment of the energy within the body, yielding order(s) of magnitude lower energy than radiative EM communication. In this work, we introduce Animal Body Communication (ABC), which utilizes the concept of using the body as a medium into the domain of untethered animal biopotential recording. This work, for the first time, develops the theory and models for animal body communication circuitry and channel loss. Using this theoretical model, a sub-inch$$^3$$ 3 [1″ × 1″ × 0.4″], custom-designed sensor node is built using off the shelf components which is capable of sensing and transmitting biopotential signals, through the body of the rat at significantly lower powers compared to traditional wireless transmissions. In-vivo experimental analysis proves that ABC successfully transmits acquired electrocardiogram (EKG) signals through the body with correlation $$>99\%$$ > 99 % when compared to traditional wireless communication modalities, with a 50$$\times$$ × reduction in power consumption.

Room-temperature white and color-tunable afterglow by manipulating multi-mode triplet emissions

2021 ◽  
Vol 9 (9) ◽  
pp. 3257-3263
Author(s):  
Jianwei Liu ◽  
Zhimin Ma ◽  
Zewei Li ◽  
Yan Liu ◽  
Xiaohua Fu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Single Component ◽  
Color Tunable ◽  
First Time ◽  
Multi Mode

Two isomers pDCzPyCN and oDCzPyCN are designed and synthesized. Amazingly, oDCzPyCN manifest white afterglow at room temperature. This is the first time that single-component white afterglow has finally been realized.

Sign in / Sign up

Export Citation Format

Share Document