BULK AND SURFACE PROPERTIES OF CZ-SILICON AFTER HYDROGEN PLASMA TREATMENTS

摘要

The properties of surface, sub-surface and bulk regions of Cz-Si were studied after plasma hydrogenation at temperatures between 25 and 450℃ and annealing up to 600℃. Investigations were done by Raman and IR-absorption spectroscopy, spreading resistance probe analysis and scanning electron microscopy. In the Si bulk a very efficient thermal donor (TD) formation occurs, resulting after 1 hour μ-wave H-plasma exposure at 450℃ in a p-n junction formation at a depth of 1.23mm due to counter doping of the p-type material by TDs. H_2-molecule formation in sub-surface layers was studied on plasma treated (at 250℃) and annealed Cz Si. H_2 molecules are located in voids/platelets, which were created by H-plasma exposures. Near the surface plasma treated samples exhibit a structuring with dimensions below 100nm. After annealing at 600℃/air this nano-structured Si exhibits a broad luminescence in the visible spectral range, which can be attributed to Si based nano-clusters.