Photoluminescence of Si nanocrystallites in different types of matrices☆
Introduction
Nanoscale silicon structures continue to be the subject of great interest. Compatibility with a well-developed Si technology makes these structures very attractive for fabrication of optoelectronics and microelectronics devices. The strong interest to this study is primarily motivated by a potential application of such systems as light emitting materials due to observation of the intense visible photoluminescence (PL) in Si nanocrystallites (nc) at room temperature. Optical properties of such systems are sensitive to nc size fluctuations, defects and surface effects due to large surface to volume ratio in small crystallites. Stable light emission of mentioned above Si structures is observed in wide spectral range: blue (∼2.64–3.0 eV), green (∼2.25 eV), orange (2.05 eV), red (1.70–1.80 eV) and infrared (1.4–1.6 eV) [1], [2], [3], [4], [5], [6], [7], [8]. These PL bands were attributed both to exciton recombination in Si nc [1], [3], [5], [6] and carrier recombination through defects inside of Si nc [2] or via oxide related defects at the Si/SiOx interface [1], [4], [7], [8]. At the same time some questions about really correlation of peak position of PL band caused by exciton recombination inside of Si nc with their sizes, the nature of another PL bands as well as relative contribution of different elementary PL bands into total PL spectrum are still not clear. The purpose of this paper is to separate elementary PL bands and to clarify the types of corresponding radiative transitions.
Section snippets
Experimental procedure
The Si-rich-SiOx systems were prepared by rf-magnetron co-sputtering from two electrodes, one with a silicon target and the other with a quartz target on a long (15 cm) quartz substrate. The change of the Si content along the layer (CSi) is calculated from the ration , where VSi and are the volumes of Si and SiO2. The technological details are presented in [1], [8]. Just after the co-sputtering process CSi varies from 71% down to 9% along the film. Following annealing at
Experimental results and discussion
PL spectra at 300 K of Si enriched silicon oxide films have shown the broad PL band with the half-width of 360–380 meV in infrared (IR) and red spectral ranges, as well as two small intensity PL bands in green–orange region (Fig. 1, curve 1). This PL spectrum can be decomposed into the five PL components peaked at 1.30, 1.50, 1.76, 2.05 and 2.32 eV (Fig. 1, curves 2–6). The relative value of 1.50 eV PL band is higher than the intensity of another four bands. Fig. 2 shows the dependence of
Acknowledgements
The work was supported by CONACYT-NSF program, project N 42436-Y, and by CGPI-IPN Mexico. The author thanks Dr Y. Matsumoto from CINVESTAV-IPN, Mexico for growing the studded amorphous silicon films and Dr J. Jedrzejewskii from Hebrew University Jerusalem, Israel for growing the studded Si-rich-SiOx systems.
References (17)
- et al.
Phys. Lett.
(2003) - et al.
Mater. Sci. Eng.
(2003) - et al.
Physica B
(2003) - et al.
Thin Solid Films
(2000) - et al.
J. Phys. Condens. Mater.
(2002) - et al.
Appl. Phys. Lett.
(1991) Appl. Phys. Lett.
(1993)- et al.
Phys. Rev. B
(1997)
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This text (O38) was presented on First Conference on Advances in Optical Materials (AIOM2005), Tucson, Arizona, USA, 12–15 October 2005.