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1.
针对多角度椭偏测量透明基片上薄膜厚度和光学参数时基片背面非相干反射光的影响问题,报道了利用椭偏透射谱测量等离子增强化学气相沉积法(PECVD)制备的a-Si:H薄膜厚度和光学参数的方法,分析了基片温度Ts和辉光放电前气体温度Tg的影响.研究表明,用椭偏透射法测量的a-Si:H薄膜厚度值与扫描电镜(SEM)测得的值相当,推导得到的光学参数与其他研究者得到的结果一致.该方法可用于生长在透明基片上的其他非晶或多晶薄膜.
关键词:
椭偏测量
透射法
光学参数
氢化非晶硅薄膜 相似文献
2.
I. Pelant P. Fojtík K. Luterová J. Kočka A. Poruba J. Štěpánek 《Applied Physics A: Materials Science & Processing》2002,74(4):557-560
A novel simple method of crystallization of hydrogenated amorphous silicon (a-Si:H) thin films is described. Namely, we studied
a metal-induced crystallization enhanced by a dc electric field in sandwich p+–i–n+structures. The samples were fabricated from wide-bandgap a-Si:H with high hydrogen content (13–51 at. % H). Macroscopic islands
of a-Si:H (up to ∼1 mm in diameter) in the region between upper (CrNi) and lower (ITO) contacts crystallize instantaneously
when a sufficiently high dc electric field (≳105 V cm-1) is applied. The crystallization sets in at room temperature and ambient atmosphere and is spatially selective. A proposed
microscopic mechanism of such an easy macroscopic crystallization consists in easy diffusion of Ni and/or Ni silicides (representing
nucleation sites) through a dense network of voids in hydrogen-rich a-Si:H.
Received: 30 November 2000 / Accepted: 3 May 2001 / Published online: 27 June 2001 相似文献
3.
Amorphous silicon-nitride thin films a-Si:N:H were obtained by plasma enhanced chemical vapour deposition (PECVD) method from
SiH4+NH3 at 13.56 MHz. The process parameters were chosen to obtain the films of properties suitable for optoelectronic and mechanical
applications. FTIR analysis of a-Si:N:H films indicated the presence of numerous hydrogen bonds (Si-H and N-H) which passivate
structural defects in multicrystalline silicon and react with impurities. The morpho-logical investigations show that the
films are homogeneous. The deposition of a-Si:N:H layers leads to the decrease in friction coefficient of used substrates.
Optical properties were optimised to obtain the films of low effective reflectivity, large energy gap Eg from 2.4 to 2.9 eV and refractive index in the range of 1.9 to 2.2. Reduction of friction coefficient for monocrystalline
silicon after covering with a-Si:N:H films was observed: from 0.25 to 0.18 for 500 cycles. 相似文献
4.
5.
A. K. Panchal D. K. Rai Meril Mathew C. S. Solanki 《Journal of nanoparticle research》2011,13(6):2469-2473
40 alternate a-Si/SiN
x
multilayer are incorporated as an absorber layer in a p–i–n solar cell. The device is fabricated using hot-wire chemical
vapor deposition (HWCVD) technique. The structure of the multilayer film is examined by high resolution transmission electron
microscopy (HR-TEM) which shows distinct formation of alternate a-Si and SiN
x
layers. The a-Si and SiN
x
layers have thickness of ~3.5 and 4 nm, respectively. The photoluminescence (PL) of multilayer film shows bandgap energy
of ~2.52 eV, is larger than that of the c-Si and a-Si. Dark and illuminated current–voltage (I–V) characterization of the ML films shows that these ML are photosensitive. In the present work, it is seen that the p–i–n
structure with i-layer as ML quantum well (QW) structures show photovoltaic effect with relatively high open-circuit voltage
(V
OC). The increment of bandgap energy in PL and high V
OC of the device is attributed to the quantum confinement effect (QCE). 相似文献
6.
NABEEL A BAKR A M FUNDE V S WAMAN M M KAMBLE R R HAWALDAR D P AMALNERKAR S W GOSAVI S R JADKAR 《Pramana》2011,76(3):519-531
Three demonstration samples of intrinsic hydrogenated amorphous silicon (a-Si:H) films were deposited using hot wire–chemical
vapour deposition (HW–CVD) technique. The optical parameters and the thickness were determined from the extremes of the interference
fringes of transmission spectrum in the range of 400–2500 nm using the envelope method. The calculated values of the refractive
index (n) were fitted using the two-term Cauchy dispersion relation and the static refractive index values (n
0) obtained were 2.799, 2.629 and 3.043 which were in the range of the reported values. The calculated thicknesses for all
samples were cross-checked with Taly-Step profilometer and found to be almost equal. Detailed analysis was carried out to
obtain the optical band gap (E
g) using Tauc’s method and the estimated values were 1.99, 2.01 and 1.75 eV. The optical band gap values were correlated with
the hydrogen content (C
H) in the samples calculated from Fourier transform infrared (FTIR) analysis. An attempt was made to apply Wemple–DiDomenico
single-effective oscillator model to the a-Si:H samples to calculate the optical parameters. The optical band gap obtained
by Tauc’s method and the static refractive index calculated from Cauchy fitting are in good agreement with those obtained
by the single-effective oscillator model. The real and the imaginary parts of dielectric constant (ε
r, ε
i), and the optical conductivity (σ) were also calculated. 相似文献
7.
Hydrogenated nanocrystalline silicon germanium thin films (nc-SiGe:H) is an interesting alternative material to replace hydrogenated
nanocrystalline silicon (nc-Si:H) as the narrow bandgap absorber in an a-Si/a-SiGe/nc-SiGe(nc-Si) triple-junction solar cell
due to its higher optical absorption in the wavelength range of interest. In this paper, we present results of optical, structural
investigations and electrical characterization of nc-SiGe:H thin films made by hot-wire chemical vapor deposition (HW-CVD)
with a coil-shaped tungsten filament and with a disilane/germane/hydrogen gas mixture. The optical band gaps of a-SiGe:H and
nc-SiGe:H thin-films, which are deposited with the same disilane/germane/hydrogen gas mixture ratio of 3.4 : 1.7 : 7, are
about 1.58 eV and 2.1 eV, respectively. The nc-SiGe:H thin film exhibits a larger optical absorption coefficient of about
2–4 in the 600–900 nm range when compared to nc-Si:H thin film. Therefore, a thinner nc-SiGe:H layer of ∼500 nm thickness
may be sufficient for the narrow bandgap absorber in an a-Si based multiple-junction solar cell. We enhanced the transport
properties as measured by the photoconductivity frequency mixing technique. These improved alloys do not necessarily show
an improvement in the degree of structural heterogeneity on the nanometer scale as measured by smallangle X-ray scattering.
Decreasing both the filament temperature and substrate temperature produced a film with relatively low structural heterogeneity
while photoluminescence showed an order of magnitude increase in defect density for a similar change in the process.
相似文献
8.
P. Danesh B. Pantchev J. Wiezorek B. Schmidt D. Grambole 《Applied Physics A: Materials Science & Processing》2011,102(1):131-135
A comparative study of hardness of thin films of hydrogenated amorphous silicon (a-Si:H) and hydrogen-free amorphous silicon
(a-Si) was carried out to reveal the role of hydrogen in the plastic properties of amorphous silicon. In addition, the effect
of hydrogen on hardness was established by changing hydrogen concentration in the material using post-deposition processing
of the samples. The hydrogen concentration in a-Si:H was decreased by thermal annealing. In a-Si hydrogen was introduced by
plasma hydrogenation. The values of hardness of the as-prepared a-Si and a-Si:H films were determined by nanoindentation using
depth profiling. Low-depth indentation was applied to evaluate the effect of post-hydrogenation. The results obtained show
that the presence of hydrogen in the amorphous silicon network leads to the increase in hardness. The conducted experiments
demonstrate that plasma hydrogenation can be used as an effective tool to increase the hardness of amorphous silicon. Hardness
of a-Si:H of about 12.3–12.7 GPa is as high as of crystalline silicon, suggesting a-Si:H can be a substitute for crystalline
silicon in some MEMS. 相似文献
9.
P. Patzner A.V. Osipov P. Hess 《Applied Physics A: Materials Science & Processing》2006,85(2):145-150
The growth of ultra-thin (<2 nm) silicon-oxide films was investigated on Si(100):H, Si(111):H, and a-Si:H surfaces in a pure water atmosphere (0.1–10 Pa) at low temperatures of 30–250 °C. Oxidation was induced photochemically by pulsed F2-laser radiation at 157 nm. The thickness and composition of the growing oxide films were monitored in real time by spectroscopic ellipsometry in the photon energy range of 1.15–4.75 eV. The mechanism of laser-induced silicon oxidation in a H2O atmosphere is shown to differ fundamentally from the classical Deal–Grove mechanism of thermal oxidation at 900–1200 °C, as well as from the photoinduced low-temperature oxidation in an O2 atmosphere. In particular, the film thickness essentially does not depend on temperature below 250 °C. A kinetic model is developed for low-temperature silicon oxidation in a H2O atmosphere. According to this model, the growth is limited at small thicknesses by the oxidation reaction and at larger thicknesses by reactions of the diffusing oxidizing species in the oxide layer. Very good agreement is established between this kinetic model and the ellipsometric measurements and the temperature and pressure dependence of the water oxidation process. PACS 82.65.+r; 07.60.Fs; 81.65.Mq; 82.50.Hp 相似文献
10.
采用对靶磁控反应溅射技术,以氢气作为反应气体在不同的氢稀释比条件下制备了氢化非晶硅薄膜.利用台阶仪、傅里叶红外透射光谱、Raman谱和紫外-可见光透射谱测量研究了不同氢稀释比对氢化非晶硅薄膜生长速率和结构特性的影响.分析结果发现,利用对靶磁控溅射技术能够实现低温快速沉积高质量氢化非晶硅薄膜的制备.随着氢稀释比不断增加,薄膜沉积速率呈现先减小后增大的趋势.傅里叶红外透射光谱表明,氢化非晶硅薄膜中氢含量先增大后变小.而Raman谱和紫外-可见光透射谱分析发现,氢稀释比的增加使氢化非晶硅薄膜有序度和光学带隙均先增大后减小.可见,此技术通过改变氢稀释比R能够实现氢化非晶硅薄膜结构的有效控制. 相似文献
11.
The paper presents the comparison of emission efficiencies for crystalline Si quantum dots (QDs) and amorphous Si nanoclusters (QDs) embedded in hydrogenated amorphous (a-Si:H) films grown by the hot wire-CVD method (HW-CVD) at the variation of technological parameters. The correlations between the intensities of different PL bands and the volumes of Si nanocrystals (nc-Si:H) and/or an amorphous (a-Si:H) phase have been revealed using X-ray diffraction (XRD) and photoluminescence (PL) methods. These correlations permit to discuss the PL mechanisms in a-Si:H films with embedded nc-Si QDs. The QD parameters of nc-Si:H and a-Si:H QDs have been estimated from PL results and have been compared (for nc-Si QDs) with the parameters obtained by the XRD method. Using PL and XRD results the relations between quantum emission efficiencies for crystalline (ηcr) and amorphous (ηam) QDs have been estimated and discussed for all studied QD samples. It is revealed that a-Si:H films prepared by HW-CVD with the variation of wire temperatures are characterized by better passivation of nonradiative recombination centers in comparison with the films prepared at the variation of substrate temperatures or oxygen flows. 相似文献
12.
Miroslav Jelinek Tomas Kocourek Josef Zemek Michal Novotný Jaromír Kadlec 《Applied Physics A: Materials Science & Processing》2008,93(3):633-637
Thin SiC
x
films were fabricated by hybrid laser–magnetron deposition system. KrF excimer laser was used for deposition of carbon and
magnetron at the same time for sputtering of Si species. Films were fabricated in argon/hydrogen ambient with and without
additional RF discharge. The substrate temperature was changed up to 700°C. Films topology, crystallinity, composition, chemical
bonds and optical emission spectra were studied. Films were smooth and amorphous. Films of thickness 400–1000 nm were fabricated.
Adhesion moved from 8 to 14 N, depending on deposition conditions. 相似文献
13.
D. He W. Cheng H. Jia E. Xie X. Chen G. Wu 《Applied Physics A: Materials Science & Processing》2001,72(4):499-501
Silicon grain arrays were prepared using a pattern crystallization technique of pulsed KrF excimer laser irradiation. The
precursor material was hydrogenated amorphous silicon (a-Si:H) thin films deposited on single crystal Si wafers by plasma-enhanced
chemical vapor deposition. It was shown that Si grains with a uniform size and a well-defined periodicity embedded in the
a-Si:H matrix were obtained by this simple technique. The grain size was less than 2 μm. Relativly strong photo-luminescence
with two peaks at 720 and 750 nm was observed at room temperature. We expect to reduce Si grain sizes by optimizing the growth
conditions of a-Si:H thin films and controlling the temperature distribution in the film during laser irradiation.
Received: 21 November 2000 / Accepted: 12 December 2000 / Published online: 9 February 2001 相似文献
14.
A.V. Osipov P. Patzner P. Hess 《Applied Physics A: Materials Science & Processing》2006,82(2):275-280
The growth of ultra-thin (<6 nm) silicon-dioxide films on Si(100):H, Si(111):H, and a-Si:H surfaces in a dry oxygen atmosphere
(0.1–10 Pa) at low temperatures (35–200 °C) was investigated. Oxidation was induced by pulsed F2-laserradiation at 157 nm. The thickness and composition of the growing films were monitored in real time by spectroscopic
ellipsometry in the photon energy range of 1.15–4.75 eV. The kinetics of low-temperature oxidation was similar for the Si
surfaces investigated and differs from that of high-temperature thermal oxidation (900–1200 °C) that can be described by the
Deal–Grove model. To explain the faster growth at the initial stage, it is proposed that oxidation occurs by diffusion of
oxygen atoms O and/or ions O-rather than oxygen molecules. The recombination of diffusive species to oxygen molecules limits their penetration into the
bulk. A diffusion model is developed for low-temperature oxidation which takes into account the recombination process of the
diffusive species. Good agreement between theory and experiment is found. The activation energy of diffusion of the active
species was found to be 0.15 eV, in agreement with previous results and recent calculations for O- ions.
PACS 82.65.+r; 07.60.Fs; 81.65.Mq; 82.50.Hp 相似文献
15.
A. E. Gorodetskii V. L. Bukhovets R. Kh. Zalavutdinov A. P. Zakharov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(6):928-934
Transport of exhausted thermonuclear fuel in the ITER divertor and pumping duct was modeled on a specially designed dc glow
discharge setup using mass spectrometry, optical and electron microscopy, and electron probe microanalysis. Transport and
deposition of hydrocarbon radicals transferred in an H2/C
x
H
yx
mixture through a hollow stainless steel anode at a total mixture pressure of 8–212 Pa and a methane content to 15 mol %
were considered. It was shown that deposition of radicals and ions (CH3, C2H3, C2H5) with kinetic energies of 0.03–3 eV on the anode inner surface at 600 K was suppressed to a large extent. In the temperature
range of 600–800 K, deposition of ions and radicals with kinetic energy of ~3 eV was partially restored with the formation
of soft a-C:H films, while thermalized radicals were not condensed. 相似文献
16.
F. Kokai K. Yamamoto Y. Koga S. Fujiwara R.B. Heimann 《Applied Physics A: Materials Science & Processing》1998,66(4):403-406
x ) films in a nitrogen atmosphere within the range 5×10-4–4×10-1 Torr. In the presence of a magnetic field, the emission intensities of N2 (second positive system) and CN species in the graphite ablation plumes were altered significantly, depending on the pressure
of the N2 environment. Corresponding to an intense CN emission, a magnetic field-induced enhancement of N incorporation – for example,
up to 37% at an N2 pressure of 300 mTorr – and the formation of sp3 tetrahedral CN bonding were both observed in the films. This suggests that the arrival of CN species at the substrate surface
with kinetic energies is important for film deposition.
Received: 27 August 1997/Accepted: 8 September 1997 相似文献
17.
We report the observation of crystallization and simultaneous formation of surface microstructures in hydrogenated amorphous
silicon (a-Si:H) thin films as one step laser processing. Light trapping microstructures of around 300 nm in height were formed
on a-Si:H films of thickness in the range of 1.5 μm to 2 μm deposited on soda lime glass after exposure to femtosecond laser
pulses. Scanning electron microscope (SEM) images show the formation of spikes that are around 1 μm part and their heights
could be controlled by the laser fluences. Atomic force microscope (AFM) images were taken to study the roughness created
on the surface. The mean roughness of the textured surface increases with laser fluence at smaller power densities, and for
power densities beyond 0.5 J/cm2 the film removal deteriorates the texturing. X-ray diffraction results indicate the formation of a nano-crystalline structure
with (111) and (311) crystal orientation after the laser treatment. The observed black color and enhanced optical absorption
in the near infrared region in laser treated films may be due to a combined effect of light trapping in the micro-structured
silicon surface because of multiple total internal reflections, phase change in the film, possible defect sites induced after
laser treatment and formation of SiOx. Demonstration of light trapping microstructures in thin a-Si:H films and simultaneous crystallization could provide new
opportunities for optoelectronic devices.
PACS 42.55.Px; 42.62.Cf; 81.05.Ge 相似文献
18.
F. Lahoz P. Haro-Gonzalez F. Rivera-López S. González-Pérez I. R. Martín N. E. Capuj C. N. Afonso J. Gonzalo J. Fernández R. Balda 《Applied Physics A: Materials Science & Processing》2008,93(3):621-625
Thin films of Er3+-doped lead–niobium germanate have been produced by pulsed laser deposition from Er3+-doped 25PbO2–25Nb2O5–50GeO2 (mol%) transparent glasses with an Er content in the range 0.5–3 wt%. The room-temperature infrared to visible upconversion
properties of these thin films have been investigated under 800-nm laser excitation. An energy transfer upconversion mechanism
has been identified to be responsible for the population of the 4S3/2:2H11/2 excited level, from which an intense green emission occurs. A rate equation analysis supports the proposed mechanism. 相似文献
19.
Hongliang Zhang Weidong Wu Chengshi Gong Wei Wang Zhibing He Jun Li Xin Ju Yongjian Tang Erqing Xie 《Applied Physics A: Materials Science & Processing》2010,98(4):895-900
Fe-doped hydrogenated amorphous carbon (a-C:H:Fe) films were deposited from a gas mixture of trans-2-butene/ferrocene/H2 by plasma enhanced metal organic chemical vapor deposition. X-ray photoelectron spectroscopy, Fourier transform infrared
spectra and Raman spectra were used to characterize the composition and the bonding structure of the a-C:H:Fe and a-C:H films.
Optical properties were investigated by the UV–visible spectroscopy and the photoluminescence (PL) spectra. The Fe-doped films
contain more aromatic structures and C=C bonds than the undoped films. The sp
2 carbon content and sp
2 clustering of the films increase, and aromatic-like rings’ structures become richer after Fe-doping. The Tauc optical gap
of the a-C:H:Fe films become narrower by 0.3 eV relative to the value of the a-C:H films. The PL peak shifts from 2.35 eV
of the a-C:H films to 1.95 eV of the a-C:H:Fe films, and the PL intensity of the a-C:H:Fe films is greatly enhanced. A deep
level emission peak around 2.04 eV of the a-C:H:Fe films is observed. 相似文献
20.
Evolution of infrared spectra and optical emission spectra in hydrogenated silicon thin films prepared by VHF-PECVD 下载免费PDF全文
A series of hydrogenated silicon thin films with varying silane concentrations have been deposited by using very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The deposition process and the silicon thin films are studied by using optical emission spectroscopy (OES) and Fourier transfer infrared (FTIR) spectroscopy, respectively. The results show that when the silane concentration changes from 10% to 1%, the peak frequency of the Si—H stretching mode shifts from 2000 cm - 1 to 2100 cm - 1, while the peak frequency of the Si—H wagging—rocking mode shifts from 650 cm - 1 to 620 cm - 1. At the same time the SiH*/Hα intensity ratio in the plasma decreases gradually. The evolution of the infrared spectra and the optical emission spectra demonstrates a morphological phase transition from amorphous silicon (a-Si:H) to microcrystalline silicon (μc-Si:H). The structural evolution and the μc-Si:H formation have been analyzed based on the variation of Hα and SiH* intensities in the plasma. The role of oxygen impurity during the plasma process and in the silicon films is also discussed in this study. 相似文献