The temperature dependence of monolayer oxidation on Si(001)-(2 × 1) studied with surface differential reflectance spectroscopy

Abstract

The initial process of dry oxidation on a Si(001)-(2×1) surface was investigated using surface differential reflectance (SDR) spectroscopy. The photon energy dependence of the difference spectra and their time courses during oxidation were analysed. It is suggested that oxidation processes at different adsorption sites can be identified from the SDR spectra. The temperature dependence of the time courses was investigated in order to obtain the activation energies. Finite activation energies for monolayer oxidation were found in the temperature range of 623-823 K, corresponding to Langmuir-type adsorption. The photon energy dependence of the activation energies could reflect the involvement of different reaction processes. Chemical reaction processes of both oxygen and silicon during oxidation in a monolayer regime are discussed.

Reactive molecular dynamics simulation of early stage of dry oxidation of Si (100) surface

“…Both oxygen atoms were then incorporated into the back bonds of the dimer row, in agreement with the previous experimental and theoretical results. 5,11,16,23,24 The oxygensilicon reaction occurred almost spontaneously within 0.5 ps at both 300 K and 1200 K. The oxidation reaction was essentially same when h ¼ 0 (Fig. 3(c) or 3(f)), except that upper oxygen atom in the molecule frequently left from the surface after the dissociation.…”

“…Initial oxidation behavior also attracts much attention due to its unique features that cannot be well described by the classical kinetic models. [6][7][8][9] A great deal of experimental investigation has been performed to resolve the oxidation state of the Si atoms in molecular level using various experimental techniques such as surface differential reflectance (SDR), 10,11 x-ray or ultraviolet photoemission spectroscopy (XPS/UPS), 8,[12][13][14][15] scanning reflection electron microscopy (SREM), 16 in situ Auger electron spectroscopy (AES) combined with reflection high energy electron diffraction (RHEED), 17 high resolution Rutherford backscattering spectrometry (HRBS), 18 or scanning tunneling microscope (STM). 6,19,20 However, the experimental observations exhibited complex behaviors of the initial oxidation phenomena, and the atomic scale computation has been expected to provide deeper insight of the reaction.…”

Theoretical Investigation of the Reaction Pathway of O Atom on Si(001)-(2 × 1)

“…Suemitu et al proposed an autocatalytic reaction model based on the DOS model and successfully explained the difference of the uptake curves between Langmuir-type adsorption and 2D island growth in the monolayer regime . Recently, these findings were also supported by optical methods, such as surface differential reflectance (SDR) spectroscopy , and reflectance difference spectroscopy (RDS) …”

“…They considered the potential energy surface (PES) of both triplet and singlet states. Experimental studies using low-temperature STM and optical spectroscopies , supported the existence of finite activation energies, although an early ultraviolet photoemission spectroscopy (UPS) study and Auger electron spectroscopy (AES) study are consistent with a barrierless process. Here we consider the case of a single O atom and do not deal with the dissociation of oxygen molecules on a Si(001) surface.…”

Reaction Kinetics in the Rapid Oxide Growth on Si(001)-(2×1) Probed with Reflectance Difference Spectroscopy

“…In the study of the initial oxidation process on Si(001)-(2Â1), real-time measurements were performed by RDS/ SDR [3][4][5]15,16) and ultraviolet/X-ray photoemission spectroscopy (UPS/XPS) [17][18][19] and Auger electron spectroscopy (AES). 20,21) In this report, we demonstrate that reaction kinetics different from a simple Langmuirian kinetics is clearly identified with RDS.…”