共查询到20条相似文献,搜索用时 359 毫秒
1.
Sk.F. Ahmed P.K. Ghosh S. Khan M.K. Mitra K.K. Chattopadhyay 《Applied Physics A: Materials Science & Processing》2007,86(1):139-143
We have observed low-macroscopic field electron emission from wide bandgap nanocrystalline Al doped SnO2 thin films deposited on glass substrates. The emission properties have been studied for different anode-sample spacings and for different Al concentrations in the films. The turn-on field and approximate work function were calculated and we have tried to explain the emission mechanism from this. The turn-on field was found to vary in the range 5.6–7.5 V/μm for a variation of anode sample spacing from 80–120 μm. The turn-on field was also found to vary from 4.6–5.68 V/μm for a fixed anode-sample separation of 80 μm with a variation of Al concentration in the films 8.16–2.31%. The Al concentrations in the films have been measured by energy dispersive X-ray analysis. Optical transmittance measurement of the films showed a high transparency with a direct bandgap ∼3.98 eV. Due to the wide bandgap, the electron affinity of the film decreased. This, along with the nanocrystalline nature of the films, enhanced the field emission properties. PACS 81.20.Fw; 61.10.-i; 79.70.+q 相似文献
2.
Ali Khademi Rouhollah Azimirad Yung-Tang Nien Alireza Z. Moshfegh 《Journal of nanoparticle research》2011,13(1):115-125
The field-emission properties of molybdenum oxide nanowires grown on a silicon substrate and its emission performance in various
vacuum gaps are reported in this article. A new kind of molybdenum oxides named nanowires with nanoscale protrusions on their
surfaces were grown by thermal vapor deposition with a length of ~1 μm and an average diameter of ~50 nm. The morphology,
structure, composition and chemical states of the prepared nanostructures were characterized by scanning electron microscopy
(SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy
(XPS). According to XRD, XPS, and TEM analyses, the synthesized samples were composed of MoO2 nanowires formed over a thin layer of crystalline Mo4O11. TEM observation revealed that these nanowires have some nanoscale protrusion on their surface. These nanoprotrusions resulted
in enhancement of field-emission properties of nanowires comprising nanoprotrusions. The turn-on emission field and the enhancement
factor of this type of nanostructures were measured 0.2 V/μm and 42991 at the vacuum gap of 300 μm, respectively. These excellent
emission properties are attributed to the special structure of the nanowires that have potential for utilizing in vacuum nanoelectronic
and microelectronic applications. 相似文献
3.
Structure and phase composition of a chromium-silicon system modified by high-current electron beams
V. V. Uglov N. T. Kvasov Yu. A. Petukhov N. N. Koval’ Yu. F. Ivanov A. D. Teresov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2012,6(1):67-72
The results of studies of the structure-phase state of a chromium-coated silicon substrate system’s subsurface layer treated
with low-energy high-current electron beams, 50–200 μs in duration and with an energy density of 15 J/cm2, are reported. The data of raster electron microscopy and X-ray structural and spectral microanalysis revealed the formation
of a chromium-doped silicon layer with a thickness of 2–38 μm, chromium-enriched silicon dendrites, chromium disilicide CrSi2, and an amorphous eutectic layer (the characteristic cross-section size of the chromium-enriched phase extrusions is ∼50
nm). The structure-phase transformations are discussed taking into account the peculiarities of the distribution of temperature,
diffusion and convective mass-transfer in the modified layer. 相似文献
4.
M. R. Kim J. Y. Kim D.-J. Jang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):279-282
Arrayed alumina nanowires having controlled uniform
diameters of 30–90 nm and lengths of 2–10 μm have been fabricated
electrochemically with a high yield using two-step anodized aluminum oxide membranes as templates. The observed photoluminescence
of the arrayed alumina nanowires arising from the emission of F+ and F centers is strong and blue-shifted compared with that of porous alumina membranes due to the structural difference
of Al2O3. Our synthesized alumina nanowires are also found to be chemically more stable than the templates. 相似文献
5.
D. Golberg P.S. Dorozhkin Y. Bando Z.-C. Dong C.C. Tang Y. Uemura N. Grobert M. Reyes-Reyes H. Terrones M. Terrones 《Applied Physics A: Materials Science & Processing》2003,76(4):499-507
Transport and field-emission properties of as-synthesized CNx and BNCx (x<0.1) multi-walled nanotubes were compared in detail. Individual ropes made of these nanotubes and macrofilms of those
were tested. Before measurements, the nanotubes were thoroughly characterized using high-resolution and energy-filtered electron
microscopy, electron diffraction and electron-energy-loss spectroscopy. Individual ropes composed of dozens of CNx nanotubes displayed well-defined metallic behavior and low resistivities of ∼10–100 kΩ or less at room temperature, whereas
those made of BNCx nanotubes exhibited semiconducting properties and high resistivities of ∼50–300 MΩ. Both types of ropes revealed good field-emission
properties with emitting currents per rope reaching ∼4 μA(CNx) and ∼2 μA (BNCx), albeit the latter ropes se- verely deteriorated during the field emission. Macrofilms made of randomly oriented CNx or BNCx nanotubes displayed low and similar turn-on fields of ∼2–3 V/μm. 3 mA/cm2 (BNCx) and 5.5 mA/cm2 (CNx) current densities were reached at 5.5 V/μm macroscopic fields. At a current density of 0.2–0.4 mA/cm2 both types of compound nanotubes exhibited equally good emission stability over tens of minutes; by contrast, on increasing
the current density to 0.2–0.4 A/cm2, only CNx films continued to emit steadily, while the field emission from BNCx nanotube films was prone to fast degradation within several tens of seconds, likely due to arcing and/or resistive heating.
Received: 29 October 2002 / Accepted: 1 November 2002 / Published online: 10 March 2003
RID="*"
ID="*"Corresponding author. Fax: +81-298/51-6280, E-mail: golberg.dmitri@nims.go.jp 相似文献
6.
Dattatray J. Late Ranjit V. Kashid Chandra Sekhar?Rout Mahendra A. More Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2010,98(4):751-756
Field emission studies of WO2.72 nanowires synthesized by a solvothermal method have been performed in the planar diode configuration under ultra high vacuum
conditions. Fowler–Nordheim plots obtained from the current-voltage characteristics follow the quantum mechanical tunneling
process and a current density of ∼8.3×106 μA/cm2 can be drawn at an applied electric field of 2 V/μm. The field enhancement factor is 33025, while the turn-on field is only
1.4 V/μm. The emission current-time plot recorded at the pre-set value of emission current of 1 μA over a period of more than
3 h exhibits an initial increase and a subsequent stabilization of the emission current. The results reveal that the WO2.72 nanowire emitters synthesized by the solvothermal method are promising cathode materials for practical applications. 相似文献
7.
Zhe Zheng Yunzhong Chen Zexiang Shen Jan Ma Chorng-Haur Sow Wei Huang Ting Yu 《Applied Physics A: Materials Science & Processing》2007,89(1):115-119
We report the synthesis of single-crystalline α-Fe2O3 nanoflakes from a simple Fe–air reaction within the temperatures range of 260–400 °C. The nanoflakes synthesized at the lowest
temperature (260 °C) in this work show an ultra-sharp morphology: 5–10 nm in thickness, 1–2 μm in length, 20 nm in base-width
and around 5 nm at the tips; successfully demonstrate the promising electron field emission properties of a large-scaled α-Fe2O3 nanostructure film and exhibit the potential applications as future field-emission (FE) electron sources and displays (FEDs).
The formation and growth of α-Fe2O3 nanostructures were discussed based on the surface diffusion mechanism.
PACS 79.60.Jv; 79.70.+q; 77.84.Bw 相似文献
8.
9.
N. G. Galkin V. M. Astashynski E. A. Chusovitin K. N. Galkin T. A. Dergacheva A. M. Kuzmitski E. A. Kostyukevich 《Journal of Applied Spectroscopy》2009,76(6):840-846
Consecutive plasma-epitaxial synthesis on silicon wafers is used for the first time to fabricate monolithic nanoheterostructures
with embedded nanocrystals (NC) of chromium disilicide (Si–NC CrSi2–Si). It is found that, initially, nanoislands form on the surface and within a coating layer of silicon, followed by the
formation of small (10–15 nm) nanocrystals of semiconducting chromium disilicide (CrSi2) at a high occupation density ((2–3)⋅1011 cm–2). During formation of silicon-silicide-silicon heterostructures, CrSi2 nanocrystallites “float up” into the near surface area of the covering silicon layer. 相似文献
10.
High-quality GaN nanowires synthesized using a CVD approach 总被引:3,自引:0,他引:3
High-quality GaN nanowires were synthesized on a large-area Si substrate by direct reaction of gallium with ammonia using
InCl3 as a catalyst. The morphology and microstructure of the resulting products were characterized using a field-emission scanning
electron microscope (SEM), a high-resolution transmission electron microscope, and X-ray diffraction (XRD). XRD and electron
diffraction revealed that the nanowires are of a hexagonal GaN phase with the wurtzite structure. The SEM study showed that
the nanowires are straight and have a smooth morphology with lengths up to 500 μm. The present results reveal that InCl3 is an optimal catalyst in GaN nanowire production.
Received: 2 April 2002 / Accepted: 12 April 2002 / Published online: 19 July 2002 相似文献
11.
X.S. Peng Y.W. Wang J. Zhang X.F. Wang L.X. Zhao G.W. Meng L.D. Zhang 《Applied Physics A: Materials Science & Processing》2002,74(3):437-439
In2O3 nanowires have been successfully fabricated on a large scale from indium particles by thermal evaporation at 1030 °C. The
as-synthesized products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission
electron microscopy (TEM). SEM and TEM images show that these nanowires are uniform with diameters of about 60–120 nm and
lengths of about 15–25 μm. XRD and selected-area electron diffraction analysis together indicate that these In2O3 nanowires crystallize in a cubic structure of the bixbyite Mn2O3 (I) type (also called the C-type rare-earth oxide structure). The growth mechanism of these nanowires is also discussed.
Received: 29 June 2001 / Accepted: 28 September 2001 / Published online: 20 December 2001 相似文献
12.
A.V. Karabutov V.D. Frolov E.N. Loubnin A.V. Simakin G.A. Shafeev 《Applied Physics A: Materials Science & Processing》2003,76(3):413-416
Low-threshold field electron emission (FEE) is reported for periodic arrays of micro-tips produced by laser ablation of Si
wafers. The best samples show emission at threshold fields as low as 4–5 V/μm for n-type Si substrates and of 1–2 V/μm for
p-doped Si substrates, as measured with a flat-screen technique. Auger electron spectroscopy and X-ray electron spectroscopy
reveal island-like deviation of the SiO2 stoichiometry on the tip surfaces, with lateral dimensions of less than 100 nm. Microscopic studies using a special field-emission
STM show that the emission originates from well-conducting regions of sub-micron size. The experimental data suggest FEE from
the tip arrays by a geometric field enhancement of both the individual micro-tip and the narrow conducting channels in the
tip body.
Received: 3 May 2002 / Accepted: 1 July 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +7-095/135-82-34, E-mail: shafeev@kapella.gpi.ru 相似文献
13.
W.M. Zhou 《Applied Surface Science》2006,253(4):2056-2058
β-SiC nanowires with an average diameter of 8-20 nm were synthesized using a simple thermal evaporation of SiO powders onto activated carbon fibers. Field emission was investigated based on the SiC nanowires deposited on a platinum film. A low turn-on field of 3.1-3.5 V μm−1 was measured at an anode-sample separation of 100-140 μm. This type of SiC nanowires can be applied as field emitters in displays as well as vacuum electronic devices. 相似文献
14.
A. Klini A. Mourka V. Dinca C. Fotakis F. Claeyssens 《Applied Physics A: Materials Science & Processing》2007,87(1):17-22
We report a method for micropatterning (25–900 μm2 pixel size) of ZnO nanorods onto a silicon substrate via a low-temperature (overall under 100 °C) two-step process, involving
a laser-based direct-write technique (laser-induced forward transfer) and sequential chemical growth. The rods produced via
this route are aligned in the [0001] crystal direction. Photoluminescence shows, next to the band-gap emission, strong green-yellow
emission centred at ∼570 nm. Additionally, the rod arrays show excellent field-emission properties with a threshold field
for emission of 5 V/μm.
PACS 61.82.Rx; 81.10.Dn; 81.16.Mk 相似文献
15.
A. V. Klochkov V. V. Naletov I. R. Mukhamedshin M. S. Tagirov D. A. Tayurskii H. Suzuki 《JETP Letters》1997,66(4):266-270
The field (0–5.5 T) and temperature (2–300 K) dependences of the magnetization of LiTmF4 powders with particle sizes of 1 μm and 56–400 μm are investigated experimentally and theoretically. It is concluded that
a transition layer exists between the thulium ions in the bulk and the ions at the surface. Two magnetic-field-induced structural
phase transitions are observed at low temperatures, and the temperature dependence of the critical magnetic fields is established.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 247–250 (25 August 1997) 相似文献
16.
Chen Hong-sheng Qi Jun-jie Zhang Yue Liao Qing-liang Huang Yun-hua 《Frontiers of Physics in China》2007,2(2):195-198
The direct growth of a tetrapod-like ZnO nanostructure has been accomplished by using a thermal oxidation method without any
catalysts. Studies on the field emission properties of the ordered ZnO nanotetrapods films found that the shape of the ZnO
nanotetrapods has considerable effect on their field emission properties, especially the turn-on field and the emission current
density. Compared with the rod-like legs ZnO nanotetrapods, the nanotetrapods with acicular legs have a lower turn-on field
of 2.7 V/μm at a current density of 10 μA/cm2, a high field enhancement factor of 1830, and an available stability. More importantly, the emission current density reached
1 mA/cm2 at a field of 4.8 V/μm without showing saturation. The results could be valuable for using the ZnO nanostructure as a cold-cathode
field-emission material.
相似文献
17.
A. G. Rousskikh A. V. Shishlov A. S. Zhigalin V. I. Oreshkin S. A. Chaikovsky R. B. Baksht 《Technical Physics》2010,55(11):1619-1627
The results of the experiments on the formation of a plasma emitter with small spatial dimensions for pulsed radiography in
the soft X-ray spectral range are presented. Emitting hot plasma was formed as a result of compression of the plasma jet by
a current pulse with amplitude I
m
= 215 kA and rise time T
fr = 200 ns. For the jet formation, we used a plasma gun based on the arc discharge (I
m
= 8.5 kA and T
fr = 6 μs) initiated by breakdown over the surface of a dielectric in vacuum. The experiments were carried out with aluminum,
tin, copper, and iron plasma jets. A single emitter, i.e., point Z-pinch (PZ-pinch), was formed when an interelectrode gap of a high current generator of 1.3–1.5 mm was used. The smallest spatial dimensions
of the emitting region were obtained with the use of aluminum and tin. For a tin jet, the diameter of the emitting region
was 7 ± 2 μm and its height was 17 ± 2 μm. The emission pulse duration at half-height was 2–3 ns. The total emission yield
per pulse in the spectral range 1.56–1.90 keV was 30–50 mJ for the aluminum pinch and 10–30 mJ for the tin pinch. The developed
method makes it possible to carry out radiographic examination of microobjects (including biological ones) 1–1000 μm in thickness,
with spatial (10–20 μm) and time (2–3 ns) resolution. 相似文献
18.
D. K. T. Ng M. H. Hong L. S. Tan Y. W. Zhu C. H. Sow 《Applied Physics A: Materials Science & Processing》2008,93(3):685-689
Patterned gallium nitride nanowires and nanodots have been grown on n-Si (100) substrates by pulsed laser deposition. The
nanostructures are patterned using a physical mask, resulting in regions of nanowire growth of different densities. The field
emission (FE) characteristics of the patterned gallium nitride nanowires show a turn-on field of 9.06 V/μm to achieve a current
density of 0.01 mA/cm2 and an enhanced field emission current density as high as 0.156 mA/cm2 at an applied field of 11 V/μm. Comparing the peak FE current densities of both the nanowires and nanodots, the peak FE current
density of nanowires is around 700 times higher than that of the peak FE current density of nanodots since nanodots have a
lower aspect ratio compared to nanowires. The field emission results indicate that, besides density difference, crystalline
quality as well as the low electron affinity of gallium nitride, high aspect ratio of gallium nitride nanostructures will
greatly enhance their field emission properties. 相似文献
19.
Yang Qiu Songliu Yuan Zhaoming Tian Liang Chen Chuanhui Wang Hanning Duan Kai Guo 《Applied Physics A: Materials Science & Processing》2012,107(2):379-383
Single phase Bi1/2Na1/2Cu3Ti4O12 (BNCTO) ceramics with different grain sizes (1.4–4.3 μm) are prepared by a modified Pechini method to investigate their giant
dielectric and nonlinear electrical behaviors. The results show that the giant dielectric and nonlinear electrical behaviors
are strongly dependent on grain size. With the increment of grain size, the dielectric constant increases monotonically from
14110 (for 1.4 μm sample) to 36183 (for 4.3 μm sample) at 1 kHz, in accompaniment with the breakdown voltage reducing from
112.5 to 43.2 V/mm and the nonlinear coefficient reducing from 4.9 to 3.4. On the basis of the internal barrier layer capacitor
(IBLC) model and the IBLC model of Schottky-type potential barrier, an interpretation of the grain size effect on the giant
dielectric and nonlinear electrical behaviors is presented. 相似文献
20.
Field emission from single-walled carbon nanotubes (SWNTs) aligned on a patterned gold surface is reported. The SWNT emitters
were prepared at room temperature by a self-assembly monolayer technique. SWNTs were cut into sub-micron lengths by sonication
in an acidic solution. Cut SWNTs were attached to the gold surface by the reaction between the thiol groups and the gold surface.
The field-emission measurements showed that the turn-on field was 4.8 V/μm at an emission current density of 10 μA/cm2. The current density was 0.5 mA/cm2 at 6.6 V/μm. This approach provides a novel route for fabricating CNT-based field-emission displays.
Received: 3 May 2002 / Accepted: 6 May 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +82-54/279-8298, E-mail: ce20047@postech.ac.kr 相似文献