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Figure 2.9: Schematic diagram of XRR set-up and the two modes of measurement. tel-00916300, version 1 - 10 Dec 2013 this critical angle gives access to the index of refraction of the surface layer by the law of Snell-Descarte (cosθ c =n). Region 2: When θ is greater than θ c , a part of the incident beam is transmitted into the layer where it undergoes multiple reections leading to the formation of interference. Since the substrate is optically denser than the lm, a phase dierence occurs at the lm surface and the substrate. The interference fringes lead to maxima and minima in the spectra. The dierence between two successive maxima in the reectivity spectra yields information on the thickness (d) of the lm or the sublayers forming the lm from the following formula, d= λ 2 √ sin 2 θ k+1 −sin 2 θ k Eqn (2.7) where λ= 1.54Å and θ k+1 and θ k represent the position of two successive maxima in the reectivity spectra. Similar calculations are done using a computer simulation in the laboratory that allows estimation of the sample thickness. For θ > θ c , the surface roughness causes a sharp decrease in the reected intensity and the other roughnesses below the surface (example: at the interfaces) reduces the amplitude of the reected peaks. If the contrast in the electronic densities of the sublayers are high enough, then their individual thicknesses can be estimated from the resulting XRR spectra as mentioned above. In the case of our samples, we can estimate only the pattern thickness. A typical XRR spectra obtained from a 14 patterned SRSO/SRSN ML grown with 4 nm SRSO and 5 nm SRSN of similar refractive indices is shown in gure 2.10 from which the total thickness and the pattern thickness (4 nm+5 nm) is estimated to a high degree of accuracy. From equation 2.7 it can 42
e seen that large θ (here, θ is used to denote the term √ sin 2 θ k+1 − sin 2 θ k ) corresponds to small thicknesses and hence from large θ we estimate the smaller pattern thickness and from small θ the total thickness. tel-00916300, version 1 - 10 Dec 2013 Figure 2.10: A typical XRR spectrum obtained from SRSO/SRSN ML with a zoom of the interferences leading to total thickness determination in the inset. (ii) In non-specular mode, the reection is obtained by xing the incident beam at θ c and moving the detector slightly around θ c , (θ c ±δθ). Rotating the detector around the critical angle enables detection of the scattered beams from a rough surface. High angular resolution is needed to separate the scattered beams from the reected ones. All the samples investigated in this thesis were analyzed using XRR in specular reection mode. Informations extracted in this thesis ˆ The thickness of each pattern in a multilayer lm. ˆ The total thickness of the lm. 2.2.4 Raman Spectroscopy Principle Raman spectroscopy is a complementary technique of FTIR and is very sensitive to homopolar bonds. Raman spectroscopy is a vibrational spectroscopic technique that relies on the principle of scattering of a monochromatic light by molecular vibrations and phonons. This scattering is classied into two parts: Elastic (Rayleigh) and 43
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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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Page 11 and 12: 3.21 Inuence of sublayer thicknesse
Page 19 and 20: Introduction State of the art tel-0
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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
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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
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Page 69 and 70: 2.2.7 Spectroscopic Ellipsometry Pr
Page 71 and 72: k(E) = f j(ω − ω g ) 2 (ω −
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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
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4.2.2 Structural analysis (a) Fouri
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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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