TY - JOUR
T1 - Single electron calculations for the Si L2, 3 near edge structure
AU - Weng, Xudong
AU - Rez, Peter
AU - Batson, P. E.
N1 - Funding Information:
The matrix element between silicon 2p and 3s wave function is about twice that between 2p and 3d. The overall differential cross section for Si L2, 3 is then the sum of the square of the matrix element multiplied by the projected density of states for the two excitation channels. The theoretical curve is compared with the experiment in Fig. 3. There, we have aligned the sharp onset of the sand d-projected DOS with the inflection point of the measured at 99.84eV. We find that the total density of final states (as shown above in Fig. 1) can be used to interpret the near edge structure only in the broadest sense of producing the right number of peaks. The curve constructed from projected DOS, on the other hand, nearly matches the positions and strengths of the four visible structures (b, c, d and e) once the initial alignment with the onset is made. In particular we should like to point out that the intensity of peak c is lower than peak b in our projected DOS calculations and the experimental result, whereas the total DOS calculations show peak c as being higher than peak b. Also the total DOS does not rise as steeply as the experimental result nor does it have the small shoulder at (a) which is present in the projected DOS results. The near edge structures (a, b) appear to arise from mainly p to s transitions, while peak c arises from mainly p to d transitions. It is possible that the addition of a small core exciton of binding energy of 50meV as reported by Carson and Schnatterly \[13\] and calculated by Alterelli and Dexter \[10\]c ould remove the remaining discrepancy between theory and experiment, for instance by enhancing the strength of the onset shoulder. However, the amount of differences that remain between the experiment and the theory are well within those differences seen among different experiments. For example, a discrepancy of 80 meV exists among various measurements of the onset inflection point \[2, 5\]. In addition, the X-ray absorption results do not give precisely the same edge shape as the energy loss experiment \[5\] when very simple and fundamental considerations suggest that they should be identical. There is still a discrepancy in the position of the maximum of peak b which might be attributed to the use of local density approximation. In conclusion, our calculation for the projected DOS for crystalline silicon demonstrates that the ground state calculation allows a relatively complete understanding of the major structures in Si at an energy resolution of 0.3 eV. Addition of an excitonic interaction will undoubtably affect the precise shape of the calculated onset region, but we do not expect major modifications of the position or strength of the major peaks. We are grateful to Dr O.F. Sankey for much help with the self-consistent PAO program. Financial support for one of us (X.W.) from National Science Foundation grants DMR-86-11609 and DMR-86-18282 is acknowledged.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 1990/6
Y1 - 1990/6
N2 - We show, for the first time, that the near edge structure of the crystalline silicon L2, 3 edge in absorption spectroscopy at an energy resolution of 0.3 eV can be largely explained without invoking many-body effects, or core excitons. Previous attempts to compare experimental results with total density of final states, without matrix element weighting, have lead to erroneous interpretations.
AB - We show, for the first time, that the near edge structure of the crystalline silicon L2, 3 edge in absorption spectroscopy at an energy resolution of 0.3 eV can be largely explained without invoking many-body effects, or core excitons. Previous attempts to compare experimental results with total density of final states, without matrix element weighting, have lead to erroneous interpretations.
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U2 - 10.1016/0038-1098(90)90476-R
DO - 10.1016/0038-1098(90)90476-R
M3 - Article
AN - SCOPUS:0025442428
SN - 0038-1098
VL - 74
SP - 1013
EP - 1016
JO - Solid State Communications
JF - Solid State Communications
IS - 9
ER -