Kinetics of oxidation on hydrogen-terminated Si(100) and (111) surfaces stored in air

Abstract

We have investigated the oxidation of hydrogen-terminated Si(111) and (100) surfaces stored in air, using synchrotron radiation photoemission spectroscopy and infrared absorption spectroscopy in the multiple internal reflection geometry. We demonstrate that water present in air is predominantly involved in the oxidation of surface Si–H bonds, and that native oxide starts to grow when the surface hydrogen coverage is decreased. In order to explain the latter phenomenon, we propose a kinetic model of oxidation which considers the manner in which native oxide formation preferentially occurs on those portions of the surface where the Si–H bonds are oxidized. We suggest that the oxidation of surface Si–H bonds, the rate of which is strongly dependent on the humidity of air, is a rate-limiting step in the native oxide formation on hydrogen-terminated Si surfaces.

Metal–insulator transition in films of doped semiconductor nanocrystals

“…The sharp peaks around 2100 cm −1 are associated with surface silicon hydride stretching modes, and features at 1000 − 800 cm −1 and 750 − 550 cm −1 are the relevant deformation modes [31]. The small peak at 2200 − 2300 cm −1 can be either Si − Px − Hy or O − Si − Hx since they appear in the same wavenumber range [32].…”

“…The sharp peaks around 2100 cm −1 are associated with surface silicon hydride stretching modes, and features at 1000 − 800 cm −1 and 750 − 550 cm −1 are the relevant deformation modes [31]. The small peak at 2200 − 2300 cm −1 can be either Si − Px − Hy or O − Si − Hx since they appear in the same wavenumber range [32].where ω is the localized surface plasmonic resonance frequency, ε is the dielectric constant for bulk Si (11.7) and ε m is the dielectric constant for the surrounding medium, taken as ∼ 1 for nitrogen atmosphere in this study. As shown in Figure 2, the plasmonic peaks are at 1110, 1260 and 1360 cm −1 in the infrared absorption spectra and the free electron concentrations are n = 1.9×10 20 , 2.4×10 20 , and 2.8 × 10 20 cm −3 for 5%, 10% and 20% P-doped Si NCs, respectively.…”

Freestanding silicon nanocrystals with extremely low defect content

“…The steps prior to the formation of Si-O-Si take place during the induction period and a larger amount of surface Si-OH groups results in a shorter t m . 40,41 Thus, the large difference in t m observed for LIDD and MIDD Si-NCs should originate from a smaller surface contamination of the LIDD Si-NCs with Si-OH groups. This is also supported by our FTIR data, where we observe the presence of surface Si-OH bonds only for the MIDD Si-NCs.…”

“…For ambient-air oxidation of bulk-Si surfaces, values ranging from 3 to 170 h have been found, depending on the Si surface index, air humidity, and the initial amount of residual Si-OH groups at the surface. [37][38][39][40][41] According to the Cabrera-Mott mechanism of ambient-air oxidation of bulk-Si and Si-NC surfaces, 20,33,45 the oxidation is initiated by adsorption of water molecules at surface Si-OH groups followed by cleavage of Si-Si backbonds of Si-OH. This is followed by electron transfer from the broken bond to an adsorbed O 2 molecule, which drifts toward the cleaved bond, leading to the oxidation of this bond and of a neighboring Si-Si bond.…”

Roles of oxygen and water vapor in the oxidation of halogen terminated Ge(111) surfaces

“…It is well known that the oxidation in the air is complicated, since oxygen, water vapor, trace oxidants such as ozone, etc., and illumination conditions can all affect the oxidation process. [8][9][10][11][12] Therefore, controlled experiments are performed to differentiate the effects of different oxidation factors. First, we perform the oxidation experiments in dark conditions, and then we repeat all the experiments with room light to study the effect of the room light illumination.…”