Measurement of Evolved Hydrogen Volume during Anodization and Its Relationship to the Anodization Process

Abstract

It has been demonstrated that two hydrogen molecules evolve per dissolved silicon atom by anodization of silicon in HF solution, although a quantitative analysis has not been performed. The relationships of the volume of evolved hydrogen atoms nH during anodization of silicon in HF solution to several anodization conditions, dissolved silicon atoms nSi and charges nhole were demonstrated. In the case of a degenerated silicon substrate, four hydrogen atoms were released as two gas molecules when a silicon atom was dissolved. In the case of a nondegenerated silicon substrate, with an increased HF concentration, the number of hydrogen atoms evolved per dissolved silicon atom was less than four, maintaining the relationship nH+2.25nhole=8.42nSi. In this study, the relationship between the number of hydrogen atoms evolved and the silicon substrate resistivity was shown experimentally.