Characterization of semiconductor interfaces by second-harmonic generation

Structure formation on the surface of indium phosphide irradiated by femtosecond laser pulses

“…21 Nevertheless, the nonlinear response of these materials is quite high 22 and there can be contributions due to surface SHG. 23 Moreover, by probing a rippled surface region (generated with five pulses at the same experimental conditions as the spot shown in Fig. 4) by micro-Raman spectroscopy over a depth of ϳ45 nm, it has been shown that besides a superficial amorphization, a polycrystalline reordering of the laser-induced resolidified melt layer underneath can also lead to crystallites with sizes between 100 and 500 nm and different orientations than the single-crystalline wafer material.…”

Spectroscopic second harmonic generation measured on plasma-deposited hydrogenated amorphous silicon thin films

“…SHG has also been applied extensively in the study of the technologically very relevant Si/ SiO 2 interface as obtained from thermal or plasma oxidation of Si wafers. 5 In contrast, the application of SHG on plasma deposited films has not been explored yet, except for the recent studies on a-SiN x : H microcavities by Lettieri et al 6 and on a-Si: H thin films by Alexandrova, Danesh, and Maslyanitsyn. 7,8 In these studies the SH signal was not rigorously characterized while for the a-Si: H films no spectral dependence of the SH signal was investigated.…”

“…This lower signal for the thicker film can (partly) be attributed to interference effects in the a-Si: H film. 5 The fact that a SH signal is observed when probing from the film-surface and substrateinterface side reveals that the SH radiation is produced in both the film-surface and substrate-interface region of the films because the SH radiation, in contrast to the pump radiation, is effectively adsorbed when passing through the a-Si: H bulk. Therefore the SH radiation generated at the substrate interface has a reduced contribution to the SH signal when probing the a-Si: H from the film-surface side and vice versa and this contribution is basically zero in the case of the 1031-nm-thick film.…”

Second harmonic surface response of a composite

“…In particular second harmonic generation (SHG) has been established as a very powerful spectroscopy to study a wide range of physical and chemical phenomena at the surface centrosymmetric materials. [1][2][3] The surface sensitivity of SHG is due to the fact that within the dipole approximation a centrosymmetric environment does not radiate SH, while the inversion symmetry is broken at its surface, thus allowing the radiation of SH. On the experimental side, the new tunable high intensity laser systems have made SHG spectroscopy readily accessible and applicable to a wide range of systems.…”

“…On the experimental side, the new tunable high intensity laser systems have made SHG spectroscopy readily accessible and applicable to a wide range of systems. 2,3 However, the theoretical development of the field is still an ongoing subject of research. Some recent advances for the case of semiconducting and metallic systems have appeared in the literature, where the confrontation of theoretical models with experiment has succeeded, yielding correct physical interpretations for the SHG spectra.…”