Second-harmonic interferometric spectroscopy of buried interfaces of column IV semiconductors

Second-harmonic intensity and phase spectroscopy as a sensitive method to probe the space-charge field in Si(100) covered with charged dielectrics

“…As the phase reference sample we use a (100 6 25) nm thick film of indium tin oxide (ITO) on a $1 mm thick glass substrate. According to Dolgova et al, 19,28 the choice of ITO, with this thickness, satisfies the conditions for a reference sample that it is (1) thin enough to avoid Maker fringes in the SH response while tuning the fundamental wavelength, (2) optically inactive to conserve the polarization state of the fundamental radiation as it passes through it, and (3) has no resonant features 3]. The phase difference (/) between the SH reference pulse and the SH pulse generated in the sample of interest is measured.…”

“…Although the SH response of the reference is expected to be spectrally flat this is not a priori imposed by using a single fit parameter E 2x reference for all interferograms. 19,28 Thus, if the tail of the resonance of ITO at $6.5 eV has some influence on the measurements within the applied two-photon energy range (2.9-3.5 eV) it can be accounted for. An excellent agreement between the data and the model can be observed for all the interferograms.…”

“…31 Note that the ITO reference sample has a flat spectral response (circular markers) which is consistent with the literature. 19,28 It must be stressed that both the SH intensity and phase spectrum can be simultaneously obtained from the interferometric measurements as represented by the data markers. The sensitivity to both intensity and phase originates from the convenient choice of placing the ITO reference sample behind the lens that focuses the fundamental beam on the sample (Fig.…”

Influence of the spatial extent of the space-charge region in c-Si on the electric-field-induced second-harmonic-generation effect

“…The parameterized model M3p strikes a good balance: it is hardly more complex than the interface-only model (M1) but yields significantly more accurate results. It can readily be adopted in the excitonic models typically used to fit SHG spectra [4,5,29,31,32,44,[46][47][48][49][50].…”

Surface–Bulk Vibrational Correlation Spectroscopy

“…Several methods have been proposed for arriving at the imaginary χ (2) spectrum. One option is to measure the phase explicitly using a heterodyne SFG experiment. − Although this has been well established for vapor–liquid and vapor–solid interfaces, it is considerably more challenging for solid–liquid interfaces. − If the phase of one of the spectral components is known (perhaps through the polarity of a certain functional group or a nonresonant background), then fitting the spectrum to a model line shape may be used to estimate the phase. − This is the most popular approach, but it is also challenging for congested spectra as the frequency and width of the resonant modes are difficult to assign unambiguously. Another option is to use Kramers–Kronig − or maximum entropy (MEM) approaches. − Each of these methods has its challenges and limitations; the suitability of a given approach depends on the nature of the question being addressed.…”