Films minces à base de Si nanostructuré pour des cellules ...

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ˆ The inuence of laser power density on the microstructure of the sample is investigated for possible laser annealing. 2.2.5 Electron Microscopy Microstructural analyses were done using High Resolution Transmission Electron Microscope (HR-TEM) and Energy-Filtered Transmission Electron Microscope (EF- TEM) 1 . The principle and working of these instruments are as detailed below and the schematic diagram is shown in gure 2.14. tel-00916300, version 1 - 10 Dec 2013 Figure 2.14: Schematic representation of light microscope, transmission electron microscope (TEM) and energy ltered TEM (EFTEM). High Resolution Transmission Electron Microscope Principle Transmission electron microscopy (TEM) technique is the most powerful one to investigate at the nanometer scale the structural properties of nanocrystals. It works on the same principle of a light microscope (optical microscope), the only dierence being the utilization of electrons instead of photons. TEMs use electrons as 'light source' and their much lower wavelength makes it possible to obtain resolutions that are a thousand times better than with a light microscope. 1 All the HRTEM observations were made by Prof X. Portier (CIMAP) and EFTEM observations by Dr. M. Carrada, CEMES, Toulouse, France. 46
Experimental set-up and working tel-00916300, version 1 - 10 Dec 2013 An electron beam, is produced by thermionic emission from a LaB 6 crystal or from a tungsten lament on application of current, and a potential dierence generated extracts the electrons. Electrons can also be produced using a eld emission gun with a tungsten tip when subjected to intense electric eld. This electron beam propagates in vacuum to illuminate the sample to be analyzed. In our laboratory JEOL 2010F set-up, the latter method is used. Instead of glass lenses focusing the light in the light microscope, the TEM uses electromagnetic lenses to focus the electrons into a very thin beam. The electron beam then interacts while travelling through the sample. Depending on the density of the material present, some of the electrons are scattered and disappear from the beam. At the bottom of the microscope the unscattered electrons hit a uorescent screen, which gives rise to a 'shadow image' of the sample with its dierent parts displayed in varied darkness according to their density. The image is then captured with a CCD camera for analysis. It is possible to observe either the image area exposed under the electron beam (image mode) or its associated diraction pattern (diraction mode). The diraction pattern also gives information on the orientation of the substrate during the observation. In Image mode, two types of contrast can be viewed. A diaphragm placed in the focal plane of the objective lens is used to select the electrons diracted in a particular direction and this image is called dark eld. The image from transmitted beam, is known as the bright eld image. Informations extracted in this thesis ˆ The crystallization and size of the Si-nps can be visualised. ˆ The total thickness of the sample, and individual sublayer thickness in a multilayer can be obtained. Energy Filtered Transmission Electron Microscope Principle Imaging Si nanoparticles in a SiO 2 (or Si 3 N 4 ) matrix by "traditional" TEM is not straightforward. Si nanocrystals exhibit only weak amplitude and phase contrast because of the small dierences in atomic number and density between Si and SiO 2 . For this reason, it is impossible to image individual Si-nps by conventional TEM (defocused bright eld or Fresnel contrast) as it is usually done for example for Ge-nps in SiO 2 . In the case of crystalline particles HR-TEM or dark eld (DF) imaging can 47
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UNIVERSITÉ de CAEN BASSE-NORMANDIE
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tel-00916300, version 1 - 10 Dec 20
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2.1.1 Radiofrequency Magnetron Reac
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3.21 Inuence of sublayer thicknesse
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Page 19 and 20: Introduction State of the art tel-0
Page 21 and 22: as the thickness of the lm, the pat
Page 23 and 24: Chapter 1 Role of Silicon in Photov
Page 25 and 26: mono-, poly- and amorphous silicon,
Page 27 and 28: Figure 1.3: A typical solar cell ar
Page 29 and 30: occurance of this three body event
Page 33 and 34: Shockley-Queisser limit of 31% [Sho
Page 41 and 42: Figure 1.12: materials. Energy diag
Page 45 and 46: Background of this thesis: A new me
Page 47 and 48: Chapter 2 Experimental techniques a
Page 49 and 50: maximum power into the plasma. (a)
Page 51 and 52: Figure 2.2: Illustration of sample
Page 53 and 54: Ray Diraction, X-Ray Reectivity, El
Page 55 and 56: (a) Normal Incidence. (b) Oblique (
Page 57 and 58: to equation 2.4, when X-ray beam st
Page 59 and 60: investigation. This value is obtain
Page 61 and 62: e seen that large θ (here, θ is u
Page 63: Figure 2.12: Raman spectrometer-Sch
Page 67 and 68: ˆ The presence of Si from SiO 2 or
Page 69 and 70: 2.2.7 Spectroscopic Ellipsometry Pr
Page 71 and 72: k(E) = f j(ω − ω g ) 2 (ω −
Page 75 and 76: Figure 2.20: Schematic diagram of t
Page 77 and 78: Chapter 3 A study on RF sputtered S
Page 79 and 80: (a) Deposition rate. (b) Refractive
Page 81 and 82: Thus, by knowing the refractive ind
Page 85 and 86: P Ar (mTorr) P H2 (mTorr) r H (%) 1
Page 87 and 88: such a peak was witnessed in [Quiro
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Page 91 and 92: initiated in this thesis, for the g
Page 93 and 94: P Si (W/cm 2 ) x = 0/Si Bruggemann
Page 97 and 98: Figure 3.15: Absorption coecient cu
Page 99 and 100: Aim of the study To see the inuence
Page 103 and 104: It can be seen that there is a sign
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Page 109 and 110: Chapter 4 A study on RF sputtered S
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(a) FTIR spectra of NRSN, Si 3 N 4
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Figure 4.15: Absorption coecient sp
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A multilayer composed of 100 patter
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multilayered conguration. Therefore
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around 1250 cm −1 . The blueshift
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tion but within a dierence of one o
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sample peak 1 (eV) peak 2 (eV) peak
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(a) 1min annealing vs. T A . (b) 1h
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(a) Brewster incidence. (b) Normal
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increases for the 50 patterned samp
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- Peak (3) and (c): 1.8-1.95 eV Die
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4.10.2 Eect of Si-np Size distribut
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Chapter 5 Photoluminescence emissio
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As seen from gure 5.1, a part of th
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function of wavelength consists of
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In the case of our multilayers, the
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⎛ ⎜ ⎝ A ′ 2 B ′ 2 1 ⎞
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dN 3 dt = N 2 τ 23 − (σ em. φ
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Figure 5.12: The shapes of k(λ) an
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5.4 Discussion on the choice of inp
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tting operations show the presence
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(a) 270nm. (b) 300nm. tel-00916300,
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(a) σ emis.max. = 8.78 x 10 −18
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(a) 50(3/1.5) (b) 50(3/3) tel-00916
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(a) Integrated population of excite
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two kinds of emitters in SRSO subla
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Conclusion and future perspectives
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4. Investigating the origin of phot
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Bibliography [Abeles 83] B. Abeles
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[Carlson 76] D. E. Carlson & C. R.
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[Di 10] D. Di, I. Perez-Wur, G. Con
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[Gritsenko 99] V. A. Gritsenko, K.
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[Kaiser 56] W. Kaiser, P. H. Kech &
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[Mandelkorn 62] J. Mandelkorn, C. M
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[Pavesi 00] L. Pavesi, L. D. Negro,
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[Sopori 96] B. L. Sopori, X. Deng,
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[Weng 93] Y. M. Weng, Zh. N. fan &
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and the tangential components of th
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Appendix II Trials σ em.max (x10
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Résumé tel-00916300, version 1 -
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