Physical properties of semi‐insulating polycrystalline silicon. III. Infrared diagnosis of the polycrystalline‐Si/c‐Si interface

In order to investigate the interface between polycrystalline‐silicon (poly‐Si) and crystalline silicon (c‐Si), which is of crucial importance for the passivation of high‐voltage devices, an infrared diagnostic method has been developed which is based on a modified attenuated total reflection configuration. This interface is shown to consist of silicon oxides (mainly SiO2) in the monolayer range with a thickness of 7±2 A. The interpretation of the experimental results is based on a direct comparison of the infrared reflectivity spectrum of the interface to be studied with that of a reference sample containing a 100‐A thick SiO2 interface layer, as well as on extensive computer calculations. Such calculations have been performed for a three‐layer system as well as for a simplified system consisting of a single absorbing layer sandwiched between two transparent half‐spaces. The latter system can be solved analytically and provides detailed insight into the physics of the interaction of light with the vibrat...