共查询到20条相似文献,搜索用时 78 毫秒
1.
High energy electron radiation effect on Ni and Ti/4H-SiCSchottky barrier diode at room temperature 下载免费PDF全文
This paper reports that Ni and Ti/4H-SiC Schottky barrier diodes
(SBDs) were fabricated and irradiated with 1~MeV electrons up to a
dose of 3.43×1014~e/cm2. After radiation, the Schottky
barrier height φ B of the Ni/4H-SiC SBD increased from
1.20~eV to 1.21~eV, but decreased from 0.95~eV to 0.94~eV for the
Ti/4H-SiC SBD. The degradation of φ B could be
explained by interface states of changed Schottky contacts. The
on-state resistance RS of both diodes increased with the
dose, which can be ascribed to the radiation defects. The reverse
current of the Ni/4H-SiC SBD slightly increased, but for the Ti/4H-SiC
SBD it basically remained the same. At room temperature,
φ B of the diodes recovered completely after one week,
and the RS partly recovered. 相似文献
2.
Judd-Oflet analysis of spectrum and laser performance of Ho:YAP crystal end-pumped by 1.91μm Tm:YLF laser 下载免费PDF全文
The Ho:YAP crystal is grown by the Czochralski technique.The room temperature polarized absorption spectra of Ho:YAP crystal was measured on a c cut sample with 1 at% holmium.According to the obtained Judd-Ofelt intensity parameters Ω2 = 1.42 × 10-20 cm2,Ω4 = 2.92 × 10-20 cm2,and Ω6 = 1.71 × 10-20 cm2,this paper calculated the fluorescence lifetime to be 6 ms for 5I7 →5 I8 transition,and the integrated emission cross section to be 2.24×10-18 cm2.It investigates the room temperature Ho:YAP laser end pumped by a 1.91 μm Tm:YLF laser.The maximum output power was 4.1 W when the incident 1.91 μm pump power was 14.4 W.The slope efficiency is 40.8%,corresponding to an optical to optical conversion efficiency of 28.4%.The Ho:YAP output wavelength was centred at 2118 nm with full width at half maximum of about 0.8 nm. 相似文献
3.
The fabrication of nickel silicide ohmic contacts to n-type 6H-silicon carbide 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper reports that the nickel silicide ohmic contacts to n-type
6H-SiC have been fabricated. Transfer length method test patterns
with NiSi/SiC and NiSi硅化镍;欧姆触点;n型碳化硅;制造;能带;带隙 Project supported by the National Basic Research Program of China (Grant
No~2002CB311904), the
National Defense Basic Research Program of China (Grant No~51327010101) and
the National Natural Science Foundation of China (Grant No~60376001). 2006-09-192006-10-30 This paper reports that the nickel silicide ohmic contacts to n-type 6H-SiC have been fabricated. Transfer length method test patterns with NiSi/SiC and NiSi2/SiC structure axe formed on N-wells created by N^+ ion implantation into Si-faced p-type 6H-SiC epilayer respectively. NiSi and NiSi2 films are prepared by annealing the Ni and Si films separately deposited. A two-step annealing technology is performed for decreasing of oxidation problems occurred during high temperature processes. The specific contact resistance Pc of NiSi contact to n-type 6H-SiC as low as 1.78× 10^-6Ωcm^2 is achieved after a two-step annealing at 350 ℃for 20 min and 950℃ for 3 min in N2. And 3.84×10-6Ωcm^2 for NiSi2 contact is achieved. The result for sheet resistance Rsh of the N+ implanted layers is about 1210Ω/□. X-ray diffraction analysis shows the formation of nickel silicide phases at the metal/n-SiC interface after thermal annealing. The surfaces of the nickel silicide after thermal annealing are analysed by scanning electron microscope. 相似文献
4.
Density functional theory (DFT) (B3P86) of Gaussian 03 has been used to optimize the structure of the Cr2 molecule, a transition metal element molecule. The result shows that the ground state for the Cr2 molecule is a 13- multiple state, indicating that there exists a spin polarization effect in the Cr2 molecule. Meanwhile, we have not found any spin pollution because the wave function of the ground state does not mingle with wave functions of higher-energy states. So the ground state for Cr2 molecule being a 13-multiple state is indicative of spin polarization effect of the Cr2 molecule among transition metal elements, that is, there are 12 parallel spin electrons in the Cr2 molecule. The number of non-conjugated electrons is greatest. These electrons occupy different spatial orbitals so that the energy of the Cr2 molecule is minimized. It can be concluded that the effect of parallel spin in the Cr2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell Sorbie potential functions with the parameters for the ground state and other states of the Cr2 molecule are derived. The dissociation energy De for the ground state of the Cr2 molecule is 0.1034eV, equilibrium bond length Re is 0.3396 nm, and vibration frequency we is 73.81cm^-1. Its force constants f2, f3 and f4 are 0.0835, -0.2831 and 0.3535 aJ. nm^-4 respectively. The other spectroscopic data for the ground state of the Cr2 molecule ωeχe, Be and αe are 1.2105, 0.0562 and 7.2938 x 10^-4cm^-1 respectively. 相似文献
5.
The splitting of potential energy curves for the states
$X^{2}\Pi _{3/2}$, $^{2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ +}$ of
hydroxyl OH under spin--orbit coupling (SOC) has been calculated by
using the SO multi-configuration quasi-degenerate perturbation theory
(SO-MCQDPT). Their Murrell--Sorbie (M--S) potential functions have been
derived, then, the spectroscopic constants for $X^{2}\Pi _{3/2}$,$^{
2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ + }$ have been derived from the
M--S function. The calculated dissociation energies for the three states are
$D_{0}$[OH($X^{2}\Pi _{3/2})$]=34966.632cm$^{-1}$,
$D_{0}$[OH($^{2}\Pi _{1/2})$]=34922.802cm$^{-1}$, and
$D_{0}$[OH($A^{2}\Sigma ^{ + })$]=17469.794cm$^{-1}$, respectively. The
vertical excitation energy $\nu [ {{ }^2\Pi _{1/2} ( {\nu = 0}
) \to {X}{ }^2\Pi _{3/2} ( {\nu = 0} )} ] =
139.6{\rm cm}^{-{\rm 1}}$. All the spectroscopic data for the
$X^{2}\Pi _{3/2}$ and $^{2}\Pi _{1/2 }$ are given for the
first time except the dissociation energy of $X^{2}\Pi _{3/2}$. 相似文献
6.
The ohmic contacts of 4H-SiC are fabricated on nitrogen ion implanted layers made by performing
box-like-profile implantation three and four times. Implantation parameters such as the standard deviation σ and the projection range Rp are calculated by the Monte Carlo simulator TRIM. Ni/Cr ohmic contacts on Si-face 4H-SiC implantation layers are measured by transfer length methods (TLMs). The results show that the values of sheet resistance Rsh are 30~kΩ /□ and 4.9~kΩ/□ and the values of specific contact resistance ρc of ohmic contacts are 7.1× 10-4Ω.cm2 and 9.5× 10-5Ω.cm2 for the implanted layers with
implantation performed three and four times respectively. 相似文献
7.
Investigations on spectroscopic parameters, vibrational levels, classical turning points and inertial rotation and centrifugal distortion constants for the X1∑+g state of sodium dimer 下载免费PDF全文
The density functional theory (B3LYP, B3P86) and the quadratic
configuration-interaction method including single and double
substitutions (QCISD(T), QCISD) presented in Gaussian03 program
package are employed to calculate the equilibrium internuclear
distance $R_{\rm e}$, the dissociation energy $D_{\rm e }$ and the
harmonic frequency $\omega _{\rm e}$ for the $X{}^{1}\Sigma^{ +
}_{\rm g}$ state of sodium dimer in a number of basis sets. The
conclusion is gained that the best $R_{\rm e}$, $D_{\rm e}$ and
$\omega _{\rm e}$ results can be attained at the
QCISD/6-311G(3df,3pd) level of theory. The potential energy curve at
this level of theory for this state is obtained over a wide
internuclear separation range from 0.16 to 2.0~nm and is fitted to
the analytic Murrell--Sorbie function. The spectroscopic parameters
$D_{\rm e}$, $D_{0}$, $R_{\rm e}$, $\omega _{\rm e}$,
$\omega _{\rm e}\chi _{\rm e}$,
$\alpha _{\rm e}$
and $B_{\rm e}$ are calculated to be 0.7219~eV,
0.7135~eV, 0.31813~nm, 151.63~cm$^{ - 1}$, 0.7288~cm$^{ - 1}$,
0.000729~cm$^{ - 1}$ and 0.1449~cm$^{ - 1}$, respectively, which are in good
agreement with the measurements. With the potential obtained at the
QCISD/6-311G(3df,3pd) level of theory, a total of 63 vibrational
states is found when $J=0$ by solving the radial Schr\"{o}dinger equation
of nuclear motion. The vibrational level, corresponding classical turning
point and inertial rotation constant are computed for each vibrational
state. The centrifugal distortion constants
($D_{\upsilon }\, H_{\upsilon }$,
$L_{\upsilon }$, $M_{\upsilon }$, $N_{\upsilon }$ and $O_{\upsilon })$ are
reported for the first time for the first 31 vibrational states when $J=0$. 相似文献
8.
We search for isotropic stochastic gravitational-wave background (SGWB) in the International Pulsar Timing Array second data release. By modeling the SGWB as a power-law, we find very strong Bayesian evidence for a common-spectrum process, and further this process has scalar transverse (ST) correlations allowed in general metric theory of gravity as the Bayes factor in favor of the ST-correlated process versus the spatially uncorrelated common-spectrum process is 30 ± 2. The median and the 90% equal-tail amplitudes of ST mode are ${{ \mathcal A }}_{\mathrm{ST}}={1.29}_{-0.44}^{+0.51}\times {10}^{-15}$, or equivalently the energy density parameter per logarithm frequency is ${{\rm{\Omega }}}_{\mathrm{GW}}^{\mathrm{ST}}={2.31}_{-1.30}^{+2.19}\times {10}^{-9}$, at frequency of 1 year−1. However, we do not find any statistically significant evidence for the tensor transverse (TT) mode and then place the 95% upper limits as ${{ \mathcal A }}_{\mathrm{TT}}\lt 3.95\times {10}^{-15}$, or equivalently ${{\rm{\Omega }}}_{\mathrm{GW}}^{\mathrm{TT}}\lt 2.16\times {10}^{-9}$, at frequency of 1 year−1. 相似文献
9.
Density functional theory (DFT) (B3p86) has been used to optimize the structure of the molecule Ta2. The result shows that the ground state of molecule Ta2 is a 7-multiple state and its electronic configuration is ^7∑u^+, which shows the spin polarization effect for molecule Ta2 of transition metal elements for the first time. Meanwhile, spin pollution has not been found because the wavefunction of the ground state does not mix with those of higher states. So, the fact that the ground state of molecule Ta2 is a 7-multiple state indicates a spin polarization effect of molecule Ta2 of the transition metal elements, i.e. there exist 6 parallel spin electrons and the non-conjugated electrons are greatest in number. These electrons occupy different space orbitals so that the energy of molecule Ta2 is minimized. It can be concluded that the effect of parallel spin of the molecule Ta2 is larger than the effect of the conjugated molecule, which is obviously related to the effect of d-electron delocalization. In addition, the Murrell-Sorbie potential functions with parameters for the ground state ^7∑u^+ and other states of the molecule Ta2 are derived. The dissociation energy De, equilibrium bond length Re and vibration frequency we for the ground state of molecule Ta2 are 4.5513eV, 0.2433nm and 173.06cm^-1, respectively. Its force constants f2, f3 and f4 are 1.5965×10^2aJ.nm^-2, -6.4722×10^3aJ·nm^-3 and 29.4851×10^4aJ·nm^-4, respectively. Other spectroscopic data we xe, Be and αe for the ground state of Ta2 are 0.2078cm^-1, 0.0315 cm^-1 and 0.7858×10^-4 cm^-1, respectively. 相似文献
10.
The comparison between single-point energy scanning (SPES) and geometry optimization (OPT) in determining the equilibrium geometry of the α^3∑u^+ state for ^7Li2 is made at numerous basis sets such as 6-311++G(2df), cc-PVTZ, 6-311++G(2df, p), 6-311G(3df,3pd), 6-311++G(2df,2pd), D95(3df,3pd), 6-311++G, DGDZVP, 6-311++G(3df,2pd), 6-311G(2df,2pd), D95V++, CEP-121G, 6-311++G(d,p), 6-311++G(2df, pd) and 6-311++G(3df,3pd) in full active space using a symmetry-adapted-cluster/ symmetry-adapted-cluster configuration-interaction (SAC/SAC=CI) method presented in Gaussian03 program package. The difference of the equilibrium geometries obtained by SPES and by OPT is reported. Analyses show that the results obtained by SPES are more reasonable than those obtained by OPT. We have calculated the complete potential energy curves at those sets over a wide internuclear distance range from about 3.0α0 to 37.0α0, and the conclusion is that the basis set cc-PVTZ is the most suitable one. With the potential obtained at ccopVTZ, the spectroscopic data (Te, De, D0, ωe,ωeХe, αe and Be) are computed and they are 1.006 eV, 338.71 cm^-1, 307.12 cm^-1, 64.88 cm^-1, 3.41 cm^-1, 0.0187 cm^-1 and 0.279 cm^-1, respectively, which are in good agreement with recent measurements. The total 11 vibrational states are found at J=0. Their corresponding vibrational levels and classical turning points are computed and compared with available RKR data, and good agreement is found. One inertial rotation constant (By) and six centrifugal distortion constants (Dr Hv, Lv, My, Nv, and Ov) are calculated. The scattering length is calculated to be -27.138α0, which is in good accord with the experimental data. 相似文献
11.
Density functional Theory (DFT) (B3p86) of Gaussian03 has been used to optimize the structure of Os2 molecule. The result shows that the ground state for Os2 molecule is 9-multiple state and its electronic configuration is ^9∑^+g, which shows spin polarization effect of Os2 molecule of transition metal elements for the first time. Meanwhile, we have not found any spin pollution because the wavefunction of the ground state does not mingle with wavefunctions with higher energy states. So, the fact that the ground state for Os2 molecule is a 9-multiple state is indicative of spin polarization effect of Os2 molecule of transition metal elements. That is, there exist 8 parallel spin electrons. The non-conjugated electron is greatest in number. These electrons occupy different spacious tracks, so that the energy of Os2 molecule is minimized. It can be concluded that the effect of parallel spin of Os2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell-Sorbie potential functions with the parameters for the ground state ^9∑^+g and other states of Os2 molecule are derived. Dissociation energy De for the ground state of Os2 molecule is 3.3971eV, equilibrium bond length Re is 0.2403nm, vibration frequency ωe is 235.32cm^-1. Its force constants f2, f3, and f4 are 3.1032×10^2aJ·nm^-2, -14.3425×10^3aJ·nm^-3 and 50.5792×10^4aJ·nm^-4 respectively. The other spectroscopic data for the ground state of Os2 molecule ωexe, Be and ae are 0.4277cm^- 1, 0.0307cm^- 1 and 0.6491 × 10^-4cm^-1 respectively. 相似文献
12.
We report the constraints of $H_0$ obtained from Wilkinson Microwave Anisotropy Probe (WMAP) 9-year data combined with the latest baryonic acoustic oscillations (BAO) measurements. We use the BAO measurements from 6dF Galaxy Survey (6dFGS), the SDSS DR7 main galaxies sample (MGS), the BOSS DR12 galaxies, and the eBOSS DR14 quasars. Adding the recent BAO measurements to the cosmic microwave background (CMB) data from WMAP, we constrain cosmological parameters $\Omega_m=0.298\pm0.005$, $H_0=68.36^{+0.53}_{-0.52} {\rm km}\cdot {\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.8170^{+0.0159}_{-0.0175}$ in a spatially flat $\Lambda$ cold dark matter ($\Lambda$CDM) model, and $\Omega_m=0.302\pm0.008$, $H_0=67.63\pm1.30 {\rm km}\cdot{\rm s}^{-1}\cdot {\rm Mpc}^{-1}$, $\sigma_8=0.7988^{+0.0345}_{-0.0338}$ in a spatially flat $w$CDM model, respectively. Our measured $H_0$ results prefer a value lower than 70 ${\rm km}\cdot {\rm s}^{-1}\cdot{\rm Mpc}^{-1}$, consistent with the recent data on CMB constraints from Planck (2018), but in $3.1$ and $3.5\sigma$ tension with local measurements of SH0ES (2018) in $\Lambda$CDM and $w$CDM framework, respectively. Our results indicate that there is a systematic tension on the Hubble constant between SH0ES and the combination of CMB and BAO datasets. 相似文献
13.
Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers 下载免费PDF全文
Wenqiang Wang 《中国物理 B》2022,31(9):97504-097504
We study inserting Co layer thickness-dependent spin transport and spin-orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy (IPMA) energy density ($K_{\rm s}= 2.7 $ erg/cm$^{2}$, 1 erg = 10$^{-7}$ J), which is dominated by interfacial spin-orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance $(G_{\mathrm{eff,tot}}^{\mathrm{\uparrow \downarrow }}=\mathrm{0.42\times }{10}^{15} \mathrm{\Omega }^{-1}\cdot\mathrm{m}^{-2}$) and two-magnon scattering ($\beta_{\mathrm{TMS}}= 0.46 {\mathrm{nm}}^{2}$) are first characterized, and the damping-like torque ($\xi_{\mathrm{DL}}= 0.103$) and field-like torque ($\xi _{\mathrm{FL}}=-0.017$) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of $\xi_{\mathrm{DL}}$ and $\xi_{\mathrm{FL}}$ in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface. 相似文献
14.
本文考虑带有黑洞视界和宇宙视界的Kiselev时空.研究以黑洞视界和宇宙视界为边界的系统的热力学性质.统一地给出了两个系统的热力学第一定律;在黑洞视界半径远小于宇宙视界半径的情况下,近似地计算了通过宇宙视界和黑洞视界的热能.然后,探讨Kiselev时空的物质吸积特性.在吸积能量密度正比于背景能量密度的条件下给出黑洞的吸积率,讨论了黑洞吸积率与暗能量态方程参数的关系. 相似文献
15.
Effect of F doping on capacitance-voltage characteristics of SiCOH low-k films metal-insulator-semiconductor structure 下载免费PDF全文
This paper investigates the capacitance--voltage
($C$--$V$) characteristics of F doping SiCOH low dielectric constant
films metal--insulator--semiconductor structure. The F doping SiCOH
films are deposited by decamethylcyclopentasiloxane (DMCPS) and
trifluromethane (CHF7755, 6855 http://cpb.iphy.ac.cn/CN/10.1088/1674-1056/19/5/057701 https://cpb.iphy.ac.cn/CN/article/downloadArticleFile.do?attachType=PDF&id=111779 F-SiCOH, low-k dielectrics, capacitance--voltage
characteristic Project supported by the National
Natural Science Foundation of China (Grant No.~10575074). 2/4/2009 12:00:00 AM This paper investigates the capacitance--voltage
($C$--$V$) characteristics of F doping SiCOH low dielectric constant
films metal--insulator--semiconductor structure. The F doping SiCOH
films are deposited by decamethylcyclopentasiloxane (DMCPS) and
trifluromethane (CHF$_{3})$ electron cyclotron resonance plasmas.
With the CHF$_{3}$/DMCPS flow rate ratio from 0 to 0.52, the
positive excursion of $C$--$V$ curves and the increase of flat-band
voltage $V_{\rm FB}$ from $-6.1$~V to 32.2~V are obtained. The
excursion of $C$--$V$ curves and the shift of $V_{\rm FB}$ are
related to the change of defects density and type at the Si/SiCOH
interface due to the decrease of Si and O concentrations, and the
increase of F concentration. At the CHF$_{3}$/DMCPS flow rate ratio
is 0.12, the compensation of F-bonding dangling bond to Si dangling
bond leads to a small $V_{\rm FB}$ of 2.0~V. 半导体结构;电压特性;电容电压;绝缘体;薄膜;金属;电子回旋共振等离子体;兴奋剂 This paper investigates the capacitance-voltage (C-V) characteristics of F doping SiCOH low dielectric constant films metal-insulator-semiconductor structure. The F doping SiCOH films are deposited by decamethylcyclopentasilox-ane [DMCPS) and trifluromethane (CHF3) electron cyclotron resonance plasmas. With the CHF3/DMCPS flow rate ratio from 0 to 0.52, the positive excursion of C-V curves and the increase of fiat-band voltage VFB from -6.1 V to 32.2V are obtained. The excursion of C-V curves and the shift of VFB are related to the change of defects density and type at the Si/SiCOH interface due to the decrease of Si and O concentrations, and the increase of F concentration. At the CHF3/DMCPS flow rate ratio is 0.12, the compensation of F-bonding dangling bond to Si dangling bond leads to a small VFB of 2.0V. 相似文献
16.
Electron tunnelling phase time and dwell time through an associated delta potential barrier 下载免费PDF全文
The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17~10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron. 相似文献
17.
The role of hydrogen in hydrogenated microcrystalline silicon film and in deposition process with VHF-PECVD technique 下载免费PDF全文
The role of hydrogen in hydrogenated microcrystalline silicon ($\mu $c-Si:H)
thin films in deposition processes with very high frequency
plasma-enhanced chemical vapour deposition (VHF-PECVD) technique have been
investigated in this paper. With \textit{in situ} optical emission spectroscopy (OES)
diagnosis during the fabrication of $\mu $c-Si:H thin films under different
plasma excitation frequency $\nu _{\rm e }$ (60MHz--90MHz), the
characteristic peak intensities ($I_{{\rm SiH}^*}$, $I_{{\rm H}\alpha^*}$
and $I_{{\rm H}\beta ^*}$) in SiHVHF-PECVD技术 氢化微晶硅 光发射光谱 薄膜学 VHF-PECVD technique, hydrogenated microcrystalline silicon, role of hydrogen, optical emission spectroscopy Project supported by the Natural Science Foundation of Guangdong
Province, China (Grant No 05300378), the State Key Development Program for Basic Research
of China (Grant Nos G2000028202 and G2000028203) and the Program on Natural
Science of Jinan University, Guangzhou, China (Grant No 51204056). 2005-11-25 2005-11-252006-01-05 The role of hydrogen in hydrogenated microcrystalline silicon (μc-Si:H) thin films in deposition processes with very high frequency plasma-enhanced chemical vapour deposition (VHF-PECVD) technique have been investigated in this paper. With in situ optical emission spectroscopy (OES) diagnosis during the fabrication of μc-Si:H thin films under different plasma excitation frequency Ve (60MHz-90MHz), the characteristic peak intensities (IsiH*, IHα* and IHβ* ) in SiH4+H2 plasma and the ratio of (IHα* + IHβ* ) to IsiH* were measured; all the characteristic peak intensities and the ratio (IHα* + IHβ* )/IsiH* are increased with plasma excitation frequency. It is identified that high plasma excitation frequency is favourable to promote the decomposition of SiH4+H2 to produce atomic hydrogen and SiHx radicals. The influences of atomic hydrogen on structural properties and that of SiHx radicals on deposition rate of μc-Si:H thin films have been studied through Raman spectra and thickness measurements, respectively. It can be concluded that both the crystalline volume fraction and deposition rate are enhanced with the increase of plasma excitation frequency, which is in good accord with the OES results. By means of FTIR measurements, hydrogen contents of μc-Si:H thin films deposited at different plasma excitation frequency have been evaluated from the integrated intensity of wagging mode near 640 cm^-1. The hydrogen contents vary from 4% to 5%, which are much lower than those of μc-Si:H films deposited with RF-PECVD technique. This implies that μc-Si:H thin films deposited with VHF-PECVD technique usually have good stability under light-soaking. 相似文献
18.
Study on spectroscopic parameters and molecular constants of HCl(X~1Σ~+) molecule by using multireference configuration interaction approach 下载免费PDF全文
Equilibrium internuclear separations, harmonic frequencies
and potential energy curves (PECs) of HCl($X^{1}\Sigma ^{ + })$
molecule are investigated by using the highly accurate valence
internally contracted multireference configuration interaction
(MRCI) approach in combination with a series of
correlation-consistent basis sets in the valence range. The PECs are
all fitted to the Murrell--Sorbie function, and they are used to
accurately derive the spectroscopic parameters ($D_{\rm e}$,
$D_{0}$, $\omega_{\rm e}\chi_{\rm e}$, $\alpha_{\rm e}$ and $B_{\rm
e})$. Compared with the available measurements, the PEC obtained at
the basis set, aug-cc-pV5Z, is selected to investigate the
vibrational manifolds. The constants $D_{0}$, $D_{\rm e}$, $R_{\rm
e}$, $\omega_{\rm e}$, $\omega_{\rm e}\chi_{\rm e}$, $\alpha_{\rm
e}$ and $B_{\rm e}$ at this basis set are 4.4006~eV, 4.5845~eV,
0.12757~nm, 2993.33~cm$^{ - 1}$, 52.6273~cm$^{ - 1}$, 0.2981~cm$^{ -
1}$ and 10.5841~cm$^{ - 1}$, respectively, which almost perfectly
conform to the available experimental results. With the potential
determined at the MRCI/aug-cc-pV5Z level of theory, by numerically
solving the radial Schr\"{o}dinger equation of nuclear motion in the
adiabatic approximation, a total of 21 vibrational levels are
predicted. Complete vibrational levels, classical turning points,
inertial rotation and centrifugal distortion constants are
reproduced, which are in excellent agreement with the available
Rydberg--Klein--Rees data. Most of these theoretical vibrational
manifolds are reported for the first time to the best of our
knowledge. 相似文献
19.
Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection 下载免费PDF全文
We study the characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh–Benard convection in′a square cavity by direct numerical simulations.The Rayleigh number range is 1×108≤Ra≤1×1013,and the Prandtl number is selected as Pr=0.7 and Pr=4.3.It is found that the temperature fluctuation profiles with respect to Ra exhibit two different distribution patterns.In the thermal boundary layer,the normalized fluctuationθrms/θrms,max is independent of Ra and a power law relation is identified,i.e.,θrms/θrms,max~(z/δ)0.99±0.01,where z/δis a dimensionless distance to the boundary(δis the thickness of thermal boundary layer).Out of the boundary layer,when Ra≤5×109,the profiles ofθrms/θrms,max descend,then ascend,and finally drop dramatically as z/δincreases.While for Ra≥1×1010,the profiles continuously decrease and finally overlap with each other.The two different characteristics of temperature fluctuations are closely related to the formation of stable large-scale circulations and corner rolls.Besides,there is a critical value of Ra indicating the transition,beyond which the fluctuation hθrmsiV has a power law dependence on Ra,given by hθrmsiV~Ra?0.14±0.01. 相似文献
20.
This paper reports that a novel type of suspended ZnO nanowire field-effect
transistors (FETs) were successfully fabricated using a
photolithography process, and their electrical properties were
characterized by I--V measurements. Single-crystalline ZnO
nanowires were synthesized by a hydrothermal method, they were used
as a suspended ZnO nanowire channel of back-gate field-effect
transistors (FET). The fabricated suspended nanowire FETs showed a
p-channel depletion mode, exhibited high on--off current ratio of
~105. When VDS=2.5 V, the peak transconductances
of the suspended FETs were 0.396 μS, the oxide capacitance was
found to be 1.547 fF, the pinch-off voltage VTH was about
0.6 V, the electron mobility was on average 50.17 cm2/Vs. The
resistivity of the ZnO nanowire channel was estimated to be
0.96× 102Ω cm at VGS = 0 V. These
characteristics revealed that the suspended nanowire FET fabricated
by the photolithography process had excellent performance. Better
contacts between the ZnO nanowire and metal electrodes could be
improved through annealing and metal deposition using a focused ion
beam. 相似文献