Transformation of Structural Defects and The Hydrogen State Upon Heat Treatment of Hydrogenated Silicon

Abstract

Transformations of structural defects, the hydrogen state, and electrophysical properties of silicon treated in hydrogen plasma are studied. Treatment in plasma (150oC) produces bands in Raman spectra at 2095 and 2129 cm–1 that are associated with scattering by Si–H vibrations. Subsequent heat treatment (275oC) causes a band for gaseous molecular H2 to appear at 4153 cm–1. A comparison of Raman spectra and scanning probe microscopy results shows that hydrogenation forms defects (platelets) of average size 43 nm and surface density 6.5·109 cm–2 that are due to precipitation of H2 and formation of Si–H bonds. Inclusions of average size 115 nm and surface density 1.7·109 cm–2 that are fi lled with molecular H2 are observed after heat treatment. The concentration of free charge carriers remains constant after treatment in plasma and subsequent heat treatment.