ANGLE-VARIABLE INFRARED EXTERNAL REFLECTION SPECTROSCOPY IN UHV AND ITS APPLICATION TO THE OBSERVATION OF SI-H VIBRATIONS ON SI(001) SUBSTRATES WITH A BURIED METAL LAYER

We have constructed a system with a variable-angle mechanism for infra red (IR) reflection spectroscopy in UHV. Hydrogen-adsorbed Si(001) sub strates with a buried metal layer (BML) are examined in vacuo to demon strate the utility of this system for surface IR spectroscopy on semic onductors. The available range of the angle is between 60 and 85 degre es, and the noise level of the 100% line after averaging 1000 scans on an Si BML substrate is <1 x 10(-4) at 2000 cm(-1) and <5 x 10(-4) at 650 cm(-1), which is sufficiently low to observe vibrations from surfa ce species at submonolayer coverage. The results show that analysis of the spectral dependence on polarization, angle of incidence and Si ov erlayer thickness is very useful in examining the origin of the signal s from surface species and their surface structures, including the ori entation.