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DS: Dünne Schichten

DS 30: Ionenimplantation III

DS 30.4: Fachvortrag

Donnerstag, 30. März 2000, 11:45–12:00, H31

Growth of β-FeSi₂ layers by ion-beam mixing — •S. Dhar¹, M. Milosavljevic^1,2, P. Schaaf¹, N. Bibic² und K.-P. Lieb¹ — ¹II. Physikalisches Institute und SFB 345, Universität Göttingen, 37073 Göttingen, Germany. — ²VINCA Institute, Belgrade, Yugoslavia

Among the next generation optoelectronic materials, β-FeSi₂ is the most promising candidate due to its unique properties and compatibility with Si device technology. It is a direct band gap (0.83-0.87 eV) semiconductor that can emit light at the wavelength of 1.5 µm. Several techniques such as ion beam synthesis, molecular beam epitaxy, etc. have been used to grow this material. However, these processes require either very high ion fluence or multi-step annealing at high temperature or a combination of both. In this study, we report on the growth of β-FeSi₂ layers by ion beam mixing of Fe/Si bilayer, using 120-350 keV Ar, Kr and Xe ions at the target temperature of 450-550^oC. Iron films of thickness 30-60 nm were deposited by e-beam evaporation. Ion energies were chosen so that the projected range is around 20 nm below the initial Fe/Si interface, and the irradiation fluences were varied from 0.5x10¹⁶ to 4x10¹⁶ ions/cm². The thickness and structure of the reacted layers were analyzed by RBS, XRD and Mössbauer spectroscopy. The results show that the complete reaction of Fe films with Si and the formation of β-FeSi₂ phase occur during ion irradiation at 450^oC for a minimum fluence of 1x10¹⁶ ion/cm². However, the most homogeneous layers of β-FeSi₂ phase are obtained after irradiation at 550^oC. In comparison to other techniques, these results demonstrate the possibility to synthesize β-FeSi₂ phase by only one processing step at relatively low temperature.