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1.
ZnS crystals grown form the vapor phase and ZnS/(001)GaAs epitaxial structures grown by metalorganic vapor phase epitaxy are studied by transmission electron microscopy after in situ irradiation in an electron microscope at an electron energy of 400 keV and intensity of (1–4) × 1019 electrons/cm2 s. It is shown that irradiation leads to the formation of small (2.5–45 nm) dislocation loops with a density of 1.4 × 1011 cm–2, as well as voids and new phase inclusions ≤10 nm in size. Using the moire fringe contrast analysis, these inclusions were identified as ZnO and ZnO2. 相似文献
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E.P. Valcheva 《Applied Physics A: Materials Science & Processing》1997,65(1):39-42
x Ga1-xAs heterojunctions grown by liquid-phase epitaxy. Interface states with hiqh concentration, Nt=3×1011 cm-2 and energy level Ec-Et=0.14 eV distributed in a box 150 Å wide at the heterointerface and acting as electron traps are observed. The possible origin
could be the isolated arsenic vacancy VAs in n-GaAs.
Received: 25 April 1996/Accepted: 22 January 1997 相似文献
4.
《Journal of Physics and Chemistry of Solids》1987,48(9):781-790
Deep Level Transient Spectroscopy (DLTS) and Optical Deep Level Transient Spectroscopy (ODLTS) experiments have been conducted on a series of In-doped CdTe crystals grown by the Bridgman or the travelling heater (THM) methods using Te as the solvent. The THM samples are n-type but strongly compensated. Annealing at 700°C under high Cd vapour pressure leads to a decompensation of the crystals. The electron concentration is then a measure of the donor (In) concentration, which was in the range 3 × 1016−1.5 × 1018cm−3. Six and eight electron traps are, respectively detected in the non-annealed and annealed samples at a concentration level 102–103 times below the net electron concentration. They cover the energy range 0.2–0.8 eV. Similar traps are found in both types of crystals, the concentration of which increases with In content and after annealing. The presence of In interstitial-type defects is suggested. A main hole trap at 0.12eV is detected by ODLTS in compensated samples with a concentration close to the donor concentration. Low temperature electrical measurements show that this trap is ionized under equilibrium conditions. It appears to be the main compensating acceptor centre. A plausible microscopic structure is IncdVcd. This study shows that In-doped CdTe grown by THM is electrically compensated and that In-containing neutral associates or precipitates play a minor role in the compensation mechanism. 相似文献
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Characteristics of charge traps in TlInS2 single crystals are investigated by the use of thermally stimulated current (TSC) technique. The TSC spectra of the sample from 80 K to 300 K are recorded at a constant heating rate. The spectra reveal that there are several trapping levels associated with the complex structure of overlapping peaks. The experimental results indicate that the traps in TlInS2 associated with the spectra in the measuring range of temperature obey the monomolecular (first order) kinetics. Thus, the spectra are resolved into first order shaped peaks by the use of computerized best fit procedure. The trapping parameters; such as the energy depth, temperature dependent frequency factor and capture cross section, together with concentrations of the corresponding six discrete levels are computed. These centers all having low capture cross sections with strong temperature dependence are found to be at the energies of 0.11 eV, 0.22 eV, 0.25 eV, 0.26 eV, 0.29 eV and 0.30 eV with high concentrations of 6.6 × 1016, 2.0 × 1017, 3.3 × 1017, 9.6 × 1016, 2.3 × 1017 and 4.0 × 1017 cm?3, respectively. 相似文献
7.
Abstract The energy shift of the He 11S0?21P1 transition, ΔE(n), can be used to determine the density, n, of He in bubbles in metals. A self-consistent band structure calculation for solid fcc He yields a linear relationship ΔE=C.n with C th=22 × 10?3 eV nm3. Systematic electron energy loss spectroscopy and transmission electron microscopy studies of He bubbles in Al for various He doses and temperatures result in Cexp=(24±8).10?3 eV nm3 in agreement with theory. The analysis is consistent with the assumption that dislocation loop punching is the dominant bubble growth mechanism during high-dose room temperature implantation. The application to He bubbles in Ni indicates a maximum He density of n=0.2 × 103 nm?3 for which He should be solid at room temperature. 相似文献
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《Journal of Physics and Chemistry of Solids》1987,48(5):447-457
The electrical properties of crystals of the ternary semiconducting compound ZnSiAs2 grown either by horizontal vapor phase transport or by the Bridgman method are reported.The resistivity and the Hall coefficient in the temperature range 77–300 K or 4.2–300 K have been measured and explained taking into account the asymmetry of the effective mass. All crystals arep-type with only one acceptor energy level between 7 × 10−3 eV and 0.32 eV, and are generally highly compensated. Annealing in zinc or arsenic vapor at 873 K induces a shift of the energy level vs annealing time.The position of the energy level vs annealing time has been explained in terms of intrinsic defects such as Schottky defects (As or Zn vacancies). The latter are accompanied by anti-structural disorder on the zinc sites. The different values of the energy levels created by the Schottky defects are attributed to a concentration effect; this may lead to the formation of an impurity band in some samples. 相似文献
9.
T. Ishida K. Maeda S. Takeuchi 《Applied Physics A: Materials Science & Processing》1980,21(3):257-261
Deformation-produced deep levels, both of electron and hole traps, have been studied using deep level transient capacitance
spectroscopy (DLTS) for an undopedn-type GaAs (HB grown) compressed at 440°C. Concentrations of two grown-in electron trap levels (E
c
−0.65eV andE
c
−0.74eV) and one grown-in hole trap level (E
v
+∼0.4eV) increase with plastic deformation, while that of a grown-in electron trap level (E
c
−∼0.3eV) decreases in an early stage of deformation. While no new peak appeared in the electron trap DLTS spectrum after plastic
deformation, in the hole trap DLTS spectrum a broad spectrum, seemingly composed of many peaks, newly appeared in a middle
temperature range, which may be attributed to electronic energy levels of dislocations with various characters. 相似文献
10.
R. Verucchi L. Aversa G. Ciullo A. Podestà P. Milani S. Iannotta 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,26(4):509-514
The development of electronic devices based on Silicon Carbide (SiC) has been strongly limited by the difficulties in growing
high quality crystalline bulk materials and films. We have recently elaborated a new technique for the synthesis of SiC on
clean Si substrates by means of supersonic beams of C60: the electronic and structural properties of the film can be controlled by monitoring the beam parameters, i.e. flux and particles energy and aggregation state. SiC films were grown in Ultra High Vacuum on Si(111)-7×7, at substrates temperatures of 800
°
C, using two different supersonic beams of C60: He and H2 have been used as seeding gases, leading to particles energy of 5 eV and 20 eV, respectively. Surface characterisation was
done in situ by Auger and X-Ray photoelectron spectroscopy, as well as by low energy electron diffraction and ex situ by atomic force microscopy technique. SiC films exhibited good structural and electronic properties, with presence of defects
different from the typical triangular voids.
Received 20 November 2001 相似文献
11.
Theoretical investigation on photovoltaic properties of PC61BM‐PDPP5T system as a promising polymer‐based solar cell
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Cai‐bin Zhao Hong‐guang Ge Zhan‐ling Wang Ling‐xia Jin Qiang Zhang Wen‐liang Wang Shi‐wei Yin 《Journal of Physical Organic Chemistry》2017,30(1)
In the current work, dependent density functional theory and time‐dependent density functional theory calculations coupled with the inherent charge hopping model and some visualization techniques have been used to systematically investigate the photovoltaic properties of PC61BM‐PDPP5T system. Calculations show that PC61BM‐PDPP5T system possesses the relatively large open‐circuit voltage 0.82 V the middle‐sized exciton binding energy (0.690 eV), the small internal reorganization energy (0.159 eV) in the exciton‐dissociation process, but the relatively large one (0.396 eV) in the case of charge‐recombination. With a simplified molecular model, the exciton‐dissociation rate constant, kdis, is estimated to be as large as 1.156 × 1010 s?1 in PC61BM‐PDPP5T phase interface, while the charge‐recombination one, krec, is only 1.018 × 107 s?1 under the same condition, which indicates a rapid and efficient photoinduced exciton‐dissociation process. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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J. Lecointre H. Cherkani-Hassani S. Cherkani-Hassani D. S. Belic J. J. Jureta P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(2):331-345
Absolute cross sections for electron-impact single ionization, dissociative
excitation and dissociative ionization of the ethynyl radical ion
(C2D+)^+) have been measured for electron energies ranging from the
corresponding reaction thresholds to 2.5 keV. The animated crossed
electron-ion beam experiment is used and results have been obtained for the
production of C2D2+, C2+, C2+_2^+ , CD+, C+ and
D+. The maximum of the cross section for single ionization is found to
be (2.01 ± 0.02) × 10-17 cm2, at the incident electron
energy of 105 eV. Absolute total cross sections for the various singly
charged fragments production are observed to decrease by a factor of almost
three, from the largest cross-section measured for C+, over C2+_2^+
and CD+ down to that of D+. The maxima of the cross sections are
obtained to be (14.5 ± 0.5) × 10-17 cm2 for C2+_2^+,
(12.1 ± 0.1) × 10-17 cm2 for CD+, (27.7 ±
0.2) × 10-17 cm2 for C+ and (11.1 ± 0.8) × 10-17 cm2 for D+.
The smallest cross section is measured to
be (1.50 ± 0.04) × 10-18 cm2 for the production of the
doubly charged ion C2+. Individual contributions for dissociative
excitation and dissociative ionization are determined for each
singly-charged product. The cross sections are presented in closed analytic
forms convenient for implementation in plasma simulation codes. Kinetic
energy release distributions of dissociation fragments are seen to extend
from 0 to 6 eV for the heaviest fragment C2+_2^+, up to 11.0 eV for
CD+, 14.2 eV for C+ and 11.2 eV for D+ products. 相似文献
15.
P. Carlsson N.T. Son F. C. Beyer H. Pedersen J. Isoya N. Morishita T. Ohshima E. Janzén 《固体物理学:研究快报》2009,3(4):121-123
Deep levels introduced by low‐energy (200 keV) electron irradiation in n‐type 4H‐SiC epitaxial layers grown by chemical vapour deposition were studied by deep level transient spectroscopy (DLTS) and photoexcitation electron paramagnetic resonance (photo‐EPR). After irradiation, several DLTS levels, EH1, EH3, Z1/2, EH5 and EH6/7, often reported in irradiated 4H‐SiC, were observed. In irradiated freestanding films from the same wafer, the EPR signals of the carbon vacancy in the positive and negative charge states, VC+ and VC‐, respectively, can be observed simultaneously under illumination with light of certain photon energies. Comparing the ionization energies obtained from DLTS and photo‐EPR, we suggest that the EH6/7 (at ~EC – 1.6 eV) and EH5 (at ~EC – 1.0 eV) electron traps may be related to the single donor (+ | 0) and the double acceptor (1– | 2–) level of VC, respectively. Judging from the relative intensity of the DLTS signals, the EH6/7 level may also be contributed to by other unidentified defects. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
16.
Mn-doped p-InSe semiconductor crystals were grown by Bridgman –Stockbarger technique. The crystals were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fabricated Sn/InSe:Mn Schottky diodes. The current–voltage (I–V) and capacitance–voltage (C–V) measurements of diodes were investigated to determine the response of devices to electron irradiation with 9?MeV energy and 1.2?×?1010?e??cm?2 dose. After irradiation, the ideality factor and barrier height of the Sn/InSe:Mn Schottky diode were determined as 1.66 and 0.85?eV, respectively. Before irradiation, they were determined as 1.37 and 0.90?eV, respectively. It has been concluded that the radiation with high energy may contribute to form defects at the interface of the Sn/InSe:Mn device. 相似文献
17.
D.C. Schmidt J.F. Barbot C. Blanchard P. Desgardin E. Ntsoenzok G. Blondiaux 《Applied Physics A: Materials Science & Processing》1997,65(4-5):403-406
9 to 1013 particles/cm2 have been investigated by the deep level transient spectroscopy technique and capacitance-voltage profiling. Under low fluence
irradiation at least four main electron traps have been observed. With further increase in irradiation fluence, two new levels
located at Ec-0.56 eV and Ec-0.64 eV appear on the high-temperature side of the DLTS signal. The slope change observed in the amplitude variations of
the singly negative charge state of the divacancy versus the dose takes place when these two new levels appear. This suggests
that both are multivacancy-related defects. After annealing at 350 °C for 15 min, all electron traps have disappeared. Moreover,
no shallow levels are created during the annealing.
Received: 12 December 1996/Accepted: 6 May 1997 相似文献
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Results are presented from the first stage of studies on the passage of an electron beam with energy 100–500 eV in a magnetic
field of 300–700 Oe through the curvilinear solenoid of the KRéL unit, the latter being a prototype of the closing segment
of the Drakon stellarator system, in the plasma-beam discharge regime. The ion density at the end of the curvilinear part
of the chamber, n
i
≈8×108–1010 cm−3, the electron temperature T
e
≈4–15 eV, and the positions at which the beam hits the target for different distances from it to the electron source are determined
experimentally. The motion of the electron beam is computationally modeled with allowance for the space charge created by
the beam and the secondary plasma. From a comparison of the experimentally measured trajectories and trajectories calculated
for different values of the space charge, we have obtained an estimate for the unneutralized ion density of the order of 5×107 cm−3.
Zh. Tekh. Fiz. 69, 22–26 (February 1999) 相似文献
20.
采用零维等离子体动力学模型,计算了不同约化场强条件下N2/O2放电等离子体的演化特性.结果表明,平均电子能量与约化场强有着近似的线性关系,在约化场强为100 Td时,平均电子能量约为2.6 eV、最大电子能量达35 eV;约化场强是影响电子能量函数分布的主要因素.气体放电过程结束后,振动激发态氮分子的粒子数浓度不再变化,电子激发态的氮分子、原子和氧原子的粒子数浓度达到一峰值后开始降低;放电结束后的氧原子通过复合反应生成臭氧.约化场强升高,由于低能电子减少的影响,振动激发态氮分子的粒子数浓度降低,当约化场强由50 Td增加75 Td,100 Td时,粒子数浓度由3.83×1011 cm-3降至1.98×1011 cm-3和1.77×1011 cm-3,其他粒子浓度则相应增大.
关键词:
等离子体
约化场强
粒子演化
数值模拟 相似文献