HYDROGEN INTERACTIONS WITH CAVITIES IN HELIUM-IMPLANTED SILICON

Hydrogen interactions with microscopic cavities in Si were quantitativ ely characterized in thermal-release experiments. Closed internal cavi ties were formed by He-ion implantation and annealing and were charact erized by transmission-electron microscopy. The isotopes protium (H-1) and deuterium (D) were introduced by ion implantation or heating in H -2 gas. During temperature ramping the redistribution and release of D were monitored by nuclear-reaction profiling, and the bonding of H-1 was selectively examined by infrared absorption spectroscopy. By explo iting the properties of closed internal surfaces this study determined the Si-H bond energy for surface monohydrides, the result being 2.5 /- 0.2 eV. Hydrogen bonded to the internal surfaces was found to lie s everal tenths of an eV lower in energy than H-2 gas and H trapped at l attice defects. The oxidized external surface of the Si specimens did not detectably impede H release, implying an efficient recombination p rocess at the Si-SiO2 interface for which possible mechanisms are cons idered.