ISSN:
1063-7826
Source:
Springer Online Journal Archives 1860-2000
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
Notes:
Abstract This paper discusses the photoluminescence spectra of 500-nm-thick layers of SiO2 implanted with Si ions at doses of 1.6×1016, 4×1016, and 1.6×1017 cm−2 and then annealed in the steady-state region (30 min) and pulsed regime (1 s and 20 ms). Structural changes were monitored by high-resolution electron microscopy and Raman scattering. It was found that when the ion dose was decreased from 4×1016 cm−2 to 1.6×1016 cm−2, generation of centers that luminesce weakly in the visible ceased. Moreover, subsequent anneals no longer led to the formation of silicon nanocrystallites or centers that luminesce strongly in the infrared. Annealing after heavy ion doses affected the photoluminescence spectrum in the following ways, depending on the anneal temperature: growth (up to ∼700 °C), quenching (at 800–900 °C), and the appearance of a very intense photoluminescence band near 820 nm (at 〉900 °C). The last stage corresponds to the appearance of Si nanocrystallites. The dose dependence is explained by a loss of stability brought on by segregation of Si from SiO2 and interactions between the excess Si atoms, which form percolation clusters. At low heating levels, the distinctive features of the anneals originate predominantly with the percolation Si clusters; above ∼700 °C these clusters are converted into amorphous Si-phase nanoprecipitates, which emit no photoluminescence. At temperatures above 900 °C the Si nanocrystallites that form emit in a strong luminescence band because of the quantum-well effect. The difference between the rates of percolation and conversion of the clusters into nanoprecipitates allows the precipitation of Si to be controlled by combinations of these annealings.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1134/1.1187595
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