Hydrogen desorption from a Si(111)1×1 surface studied by sum frequency generation spectroscopy and microscopy

Abstract

We studied isothermal hydrogen desorption from a Si(111)1Â1 surface at temperatures of~711, 732, 752, and 771 K by observing sum frequency generation (SFG). Peak shift and width broadening of the Si-H vibration occurred with increase of heating time. We also obtained SFG intensity images of monohydride species on the surface after heating for 10 s at temperatures of 592, 625, 666, 728, and 752 K. The SFG intensity images with a spatial resolution of 5 mm indicated that the hydrogen desorption was homogeneous. This result suggests that the hydrogen atoms diffused homogeneously on the Si(111)1Â1 surface.

Hydrogen desorption kinetics from H‐Si (111) surfaces studied by optical sum frequency generation and second harmonic generation

“…The resistivity of the samples was 1 ~ 5 Ω cm. Sample preparation and hydrogen termination were reported in detail by Hien et al Here, we will describe in detail the SFG and SHG measurements. The optical system is shown in Fig.…”

“…The peak at 2083.7 cm −1 is assigned to the stretching vibration of monohydride on the Si surface. This result is consistent with the literature . In general, the hydrogen coverage θ can be estimated approximately from the peak height of SFG peaks by the following expression as Here, I SFG is the peak height and is the nonlinear susceptibility.…”

“…studied isothermal hydrogen desorption from a H‐Si (111)1 × 1 surface prepared by chemical etching by using sum frequency generation (SFG) spectroscopy at different temperatures. They suggested that the hydrogen desorbed homogeneously, but they could not decide the desorption order at hydrogen coverage below 0.2 ML, because at the coverage lower than 0.2 ML, the resonant SFG signal was indistinguishable from the non‐resonance background. The surface coverage corresponding to ∼1 ML is the maximum surface density of the hydrogen atoms on the Si (111) surface, namely, 1 ML = 7.8 × 10 14 (atoms/cm 2 ) …”

Sum frequency generation spectroscopy study of hydrogenated stepped Si(111) surfaces made by molecular hydrogen exposure

“…The A peak at 2082 cm -1 is attributed to the terrace vibrational stretching monohydride as it is consistent with that in IR [4,5,27], Raman [16], other SFG spectra [13,28,29] of the vicinal Si surface, and also the flat Si surface shown in Fig. 5 [23]. The C 1 peak at 2094 cm -1 is attributed to isolated SiH C of step dihydride and has never been reported in SFG spectra.…”

“…2, the ssp-SFG spectrum of a flat H-Si(111)1x1 surface previously observed by our group is shown in Fig. 5 [23]. The black dots are experimental results and the solid curve is a Gaussian fitting curve.…”