scholarly journals The Electronic Properties of Silicon Nanowires during Their Dissolution under Simulated Physiological Conditions

2019 ◽  
Vol 9 (4) ◽  
pp. 804
Author(s):  
Annina Steinbach ◽  
Tanja Sandner ◽  
Madeleine Nilsen ◽  
Ximeng Hua ◽  
Ragul Sivakumar ◽  
...  
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Electronic Properties ◽  
Silicon Nanowires ◽  
Silicon Nanowire ◽  
Conduction Band Edge ◽  
Surface Band ◽  
Nanowire Diameter ◽  
Biomedical Sensors ◽  
Physiological Conditions

Silicon nanowires are considered promising future biomedical sensors. However, their limited stability under physiological conditions poses a challenge in sensor development and necessitates a significantly improved knowledge of underlying effects as well as new solutions to enhance silicon nanowire durability. In the present study, we deduced the dissolution rates of silicon nanowires under simulated physiological conditions from atomic force microscopy measurements. We correlated the relevant change in nanowire diameter to changes in the electronic properties by examining the I-V characteristics of kinked silicon nanowire p–n junctions. Contact potential difference measurements and ambient pressure photoemission spectroscopy additionally gave insights into the electronic surface band structure. During the first week of immersion, the Fermi level of n-type silicon nanowires shifted considerably to higher energies, partly even above the conduction band edge, which manifested in an increased conductivity. After about a week, the Fermi level stabilized and the conductivity decreased consistently with the decreasing diameter caused by continuous nanowire dissolution. Our results show that a physiological environment can substantially affect the surface band structure of silicon nanowire devices, and with it, their electronic properties. Therefore, it is necessary to study these effects and find strategies to gain reliable biomedical sensors.

CHANGES INDUCED IN THE SURFACE ELECTRONIC STRUCTURE OF Be(0001) AFTER Si ADSORPTION

2002 ◽  
Vol 09 (02) ◽  
pp. 687-691
Author(s):  
L. I. JOHANSSON ◽  
C. VIROJANADARA ◽  
T. BALASUBRAMANIAN
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Band Gap ◽  
Electronic Properties ◽  
Surface State ◽  
Core Level ◽  
Clean Surface ◽  
Core Level Spectrum ◽  
Surface Band ◽  
Surface Electronic Structure

A study of effects induced in the Be 1s core level spectrum and in the surface band structure after Si adsorption on Be(0001) is reported. The changes in the Be 1s spectrum are quite dramatic. The number of resolvable surface components and the magnitude of the shifts do decrease and the relative intensities of the shifted components are drastically different compared to the clean surface. The surface band structure is also strongly affected after Si adsorption and annealing. At [Formula: see text] the surface state is found to move down from 2.8 to 4.1 eV. The band also splits at around 0.5 Å-1 along both the [Formula: see text] and [Formula: see text] directions. At [Formula: see text] and beyond [Formula: see text] only one surface state is observed in the band gap instead of the two for the clean surface. Our findings indicate that a fairly small amount of Si in the outer atomic layers strongly modifies the electronic properties of these layers.

scholarly journals Silicon Nanowires: A Breakthrough for Thermoelectric Applications

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5305
Author(s):  
Giovanni Pennelli ◽  
Elisabetta Dimaggio ◽  
Antonella Masci
Keyword(s):  
Integrated Circuits ◽  
Power Factor ◽  
Silicon Nanowires ◽  
Silicon Nanowire ◽  
Large Temperature ◽  
Nanowire Diameter ◽  
Large Numbers ◽  
High Power Factor ◽  
Experimental Works ◽  
Very High

The potentialities of silicon as a starting material for electronic devices are well known and largely exploited, driving the worldwide spreading of integrated circuits. When nanostructured, silicon is also an excellent material for thermoelectric applications, and hence it could give a significant contribution in the fundamental fields of energy micro-harvesting (scavenging) and macro-harvesting. On the basis of recently published experimental works, we show that the power factor of silicon is very high in a large temperature range (from room temperature up to 900 K). Combining the high power factor with the reduced thermal conductivity of monocrystalline silicon nanowires and nanostructures, we show that the foreseen figure of merit ZT could be very high, reaching values well above 1 at temperatures around 900 K. We report the best parameters to optimize the thermoelectric properties of silicon nanostructures, in terms of doping concentration and nanowire diameter. At the end, we report some technological processes and solutions for the fabrication of macroscopic thermoelectric devices, based on large numbers of silicon nanowire/nanostructures, showing some fabricated demonstrators.

SILICON NANOWIRES FORMATION IN CMOS COMPATIBLE MANNER

2006 ◽  
Vol 05 (04n05) ◽  
pp. 445-451 ◽  
Author(s):  
AJAY AGARWAL ◽  
N. BALASUBRAMANIAN ◽  
N. RANGANATHAN ◽  
R. KUMAR
Keyword(s):  
Silicon Nanowires ◽  
Silicon Nanowire ◽  
Electrical Characterization ◽  
Single Electron Transistor ◽  
Bulk Silicon ◽  
Nanowire Diameter ◽  
Section Shape ◽  
Medical Sensors ◽  
Cmos Compatible

We present CMOS compatible fabrication technique for silicon nanowire ( SiNW ) on bulk silicon wafers. Our method uses saw-tooth etch-profiles of fins followed by self-limiting oxidation to form vertically self-aligned horizontal SiNW down to 5 nm diameter. The concept of modifying the cross-section shape of SiNW from triangular to circular and the ability to achieve desired nanowire diameter are unique in this work. Nanowires formed by such technique can be utilized to realize several nanoelectronics devices like gate-all-around transistor, single-electron-transistor, etc.; NEMS and bio-medical sensors; all in a CMOS friendly manner. The physical and electrical characterization of the SiNW is also presented in this paper.

Effects of n-Type Dopants on Electronic Properties in 4H-SiC

2015 ◽  
Vol 645-646 ◽  
pp. 325-329
Author(s):  
Jin Long Tang ◽  
Jun Nan Zhong ◽  
Cai Wen
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Band Gap ◽  
Electronic Properties ◽  
Density Of States ◽  
First Principles ◽  
Electronic Structures ◽  
Doping Concentration ◽  
Impurity Level ◽  
First Principles Calculations

Based on first-principles calculations, we have investigated atomic and electronic structures of 4H-SiC crystal doped by N, P and As elements as n-type dopants. We have obtained the bond lengths of the optimization system, as well as the impurity levels, the band structure and the density of states. The results show that the higher impurity level above the Fermi level is observed when 4H-SiC doped by N with concentration as 6.25% in these dopants, and the band gap of 4H-SiC decreases while the doping concentration or the atomic number of dopant increases.

scholarly journals Tuning Electronic Properties of the SiC-GeC Bilayer by External Electric Field: A First-Principles Study

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 309
Author(s):  
Min Luo ◽  
Bin Yu ◽  
Yu-e Xu
Keyword(s):  
Band Structure ◽  
Electric Field ◽  
Fermi Level ◽  
Electronic Properties ◽  
External Electric Field ◽  
Valence Band ◽  
Conduction Band ◽  
First Principles ◽  
First Principles Calculations ◽  
Direct Bandgap

First-principles calculations were used to investigate the electronic properties of the SiC/GeC nanosheet (the thickness was about 8 Å). With no electric field (E-field), the SiC/GeC nanosheet was shown to have a direct bandgap of 1.90 eV. In the band structure, the valence band of the SiC/GeC nanosheet was mainly made up of C-p, while the conduction band was mainly made up of C-p, Si-p, and Ge-p, respectively. Application of the E-field to the SiC/GeC nanosheet was found to facilitate modulation of the bandgap, regularly reducing it to zero, which was linked to the direction and strength of the E-field. The major bandgap modulation was attributed to the migration of C-p, Si-p, and Ge-p orbitals around the Fermi level. Our conclusions might give some theoretical guidance for the development and application of the SiC/GeC nanosheet.

scholarly journals Tunable Electronic Properties of Nitrogen and Sulfur Doped Graphene: Density Functional Theory Approach

Nanomaterials ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 268 ◽  
Author(s):  
Ji Lee ◽  
Sung Kwon ◽  
Soonchul Kwon ◽  
Min Cho ◽  
Kwang Kim ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Band Structure ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Functional ◽  
Pristine Graphene ◽  
Theory Approach ◽  
Functional Theory ◽  
Doped Graphene ◽  
P Type

We calculated the band structures of a variety of N- and S-doped graphenes in order to understand the effects of the N and S dopants on the graphene electronic structure using density functional theory (DFT). Band-structure analysis revealed energy band upshifting above the Fermi level compared to pristine graphene following doping with three nitrogen atoms around a mono-vacancy defect, which corresponds to p-type nature. On the other hand, the energy bands were increasingly shifted downward below the Fermi level with increasing numbers of S atoms in N/S-co-doped graphene, which results in n-type behavior. Hence, modulating the structure of graphene through N- and S-doping schemes results in the switching of “p-type” to “n-type” behavior with increasing S concentration. Mulliken population analysis indicates that the N atom doped near a mono-vacancy is negatively charged due to its higher electronegativity compared to C, whereas the S atom doped near a mono-vacancy is positively charged due to its similar electronegativity to C and its additional valence electrons. As a result, doping with N and S significantly influences the unique electronic properties of graphene. Due to their tunable band-structure properties, the resulting N- and S-doped graphenes can be used in energy and electronic-device applications. In conclusion, we expect that doping with N and S will lead to new pathways for tailoring and enhancing the electronic properties of graphene at the atomic level.

The Surface Electronic Band Structure CoS2(001)

2008 ◽  
Vol 1119 ◽  
Author(s):  
Ning Wu ◽  
Ya. B. Losovyj ◽  
Michael Manno ◽  
Chris Leighton ◽  
Peter Dowben
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Single Crystal ◽  
Brillouin Zone ◽  
Electronic Band Structure ◽  
Exchange Splitting ◽  
High Quality ◽  
Surface Band ◽  
Electronic Band ◽  
Surface Brillouin Zone

AbstractAngle-resolved photoemission was used to study the surface electronic band structure of ferromagnetic CoS2(below 120K) in high-quality single crystal samples. Strongly dispersing Co t2g bands are identified along the <100> k// direction. Fermi level crossings are identified along this Γ - X line (of the surface Brillouin zone) in higher resolution photoemission spectra, suggesting that the overall polarization may be controlled by the details of the band structure, particularly the surface band structure, rather than by exchange splitting on the Co atoms.

A Systematic Study of Metal-assisted Chemical Etching Parameters for Well-Ordered Silicon Nanowire Array Fabrication

2012 ◽  
Vol 1408 ◽  
Author(s):  
Arif S. Alagoz ◽  
Tansel Karabacak
Keyword(s):  
Silicon Nanowires ◽  
Chemical Etching ◽  
Crystalline Silicon ◽  
Silicon Nanowire ◽  
Etching Rate ◽  
Nanowire Array ◽  
Lithium Ion ◽  
Nanowire Diameter ◽  
Silicon Nanowire Array ◽  
Metal Assisted Chemical Etching

ABSTRACTMetal-assisted chemical etching is a simple and low-cost silicon nanowire fabrication method which allows control of nanowire diameter, length, shape and orientation. In this work, we fabricated well-ordered silicon nanowire array by patterning gold thin film by nanosphere lithography and etching single crystalline silicon wafer by metal-assisted chemical etching technique. We investigated relation between etched solution concentration and nanowire morphology, wafer crystal orientation, etching rate. This well-ordered silicon nanowires arrays have the potential applications in many fields but especially next generation energy related applications from solar cells to lithium-ion batteries.

THE SURFACE BAND STRUCTURE OF Li/Be$(10\bar{1}0)$

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1493-1496
Author(s):  
L. I. JOHANSSON ◽  
T. BALASUBRAMANIAN ◽  
C. VIROJANADARA
Keyword(s):  
Band Structure ◽  
Fermi Level ◽  
Surface State ◽  
Room Temperature ◽  
Surface States ◽  
High Symmetry ◽  
Clean Surface ◽  
Surface Band ◽  
State Band ◽  
Li Adsorption

A photoemision study of the surface states on Be[Formula: see text] after Li adsorption at room temperature is reported. The surface band structure was mapped along four high symmetry directions of the SBZ. Fairly large shifts in the surface band locations were obtained but all surface states observed experimentally after Li adsorption were found to correspond to Be-derived states and no Li-derived surface states could be identified. The surface state bands located close to the Fermi level (E F ) were found to be affected the most and it is suggested that one surface state band which on the clean surface is located above E F is pulled down below E F after Li adsorption.

scholarly journals Structure-Dependent 4-Tert-Butyl Pyridine-Induced Band Bending at TiO2Surfaces

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Mats Göthelid ◽  
Shun Yu ◽  
Sareh Ahmadi ◽  
Chenghua Sun ◽  
Marcelo Zuleta
Keyword(s):  
Fermi Level ◽  
Photoelectron Spectroscopy ◽  
Oxygen Vacancies ◽  
Conduction Band Edge ◽  
Excess Charge ◽  
Positive Role ◽  
Surface Band ◽  
Band Bending ◽  
Tert Butyl ◽  
Cell Electrolytes

The role of 4-tert butyl pyridine (4TBP) adsorption on TiO2surface band bending has been studied using photoelectron spectroscopy. Surface oxygen vacancies pin the Fermi level near the conduction band edge on rutile (110). 4TBP preferentially adsorbs in those vacancies and shift the Fermi level to lower binding energy in the band gap. This is done by transferring vacancy excess charge into the emptyπ∗orbital in the pyridine ring. The anatase (100) surface contains much less oxygen vacancies although the surface is much rougher than the rutile (110). 4TBP adsorption does not have any significant effect on the surface band bending. Thus the positive role associated with 4TBP addition to solar cell electrolytes is suggested to protection against adsorption of other electrolyte components such as Li and I.

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