Infrared Spectroscopy of Si(111) and Si(100) Surfaces After HF Treatment: Hydrogen Termination and Surface Morphology
- PDF / 878,575 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 67 Downloads / 205 Views
INFRARED SPECTROSCOPY OF Si(111) AND Si(100) SURFACES AFTER HF TREATMENT: HYDROGEN TERMINATION AND SURFACE MORPHOLOGY Y. J. CHABAL, G. S. HIGASHI AND K. RAGHAVACHARI AT&T Bell Laboratories, Murray Hill, NJ 07974
ABSTRACT The methodology for extracting structural information from surface infrared spectra is exemplified by considering the silicon-hydrogen stretching modes of flat and vicinal Si(111) and Si(100) surfaces obtained after HF treatment.
INTRODUCTION Chemical preparation of semiconductor surfaces is a necessary first step in device technology. In fact the influence of chemical treatments on the electronic properties of semiconductor surfaces was pointed out as early as 1958.(1) Recently, surface recombination measurements have revealed that chemically oxidized and subsequently HF-stripped Si surfaces (RCA cleaning technique(2 )) are nearly perfect electronic interfaces(3), terminated mostly by atomic hydrogen.(3 6) Despite the importance of understanding the microscopic nature of these chemically prepared surfaces, little is known because few probes can investigate the surfaces in situ (e.g., in the solution and after treatment at atmosphere pressure). Partial information (e.g. after introducing the sample into a UHV chamber) may not describe the original state well because contamination may occur during the pumping process. As a result, there is a need for several experimental probes. Among them, optical techniques have the advantage of being non-destructive and compatible with investigations at atmospheric pressure. The purpose of this paper is to outline the methodology involved with one of such optical spectroscopies: surface infrared spectroscopy. The details of the analysis have already been reported in refs. (5) and (6).
EXPERIMENTAL An important aspect of infrared spectroscopy of semiconductor surfaces is the use of a polarized multiple internal reflection (MIR) geometry.(7) The internal reflection provides sensitivity to vibrational components parallel to the surface, multiple reflections enhance the overall sensitivity and polarized 8 radiation separates all components of the spectra.( ) To illustrate this point, we consider the geometry used in our experiment: 3.8 cm X 1.9 cm X
Data Loading...
