The strong blue and red electroluminescence from Eu-implanted SiO2 layers were investigated as a function of implantation and annealing conditions. It is shown that the red electroluminescence assigned to Eu3+ ions is favored by low Eu concentrations, low annealing temperatures, and short annealing times. Based on a more quantitative analysis of the electroluminescence spectra this preference is explained by a shorter supply of oxygen for higher Eu concentrations and the growth of Europium or Europium oxide clusters with increasing annealing temperatures and annealing times. The correlation between electroluminescence and microstructure is supported by transmission electron microscopy investigations and demonstrates that the electroluminescence of Eu-implanted SiO2 layers can serve as a probe for the microstructural development in the active layer of the light emitter.

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Articles you may be interested inComparison of electrical and electro-optical characteristics of light-emitting capacitors based on silicon-rich Sioxide fabricated by plasma-enhanced chemical vapor deposition and ion implantationThe effect of rare-earth clustering on charge trapping and electroluminescence in rare-earth implanted metaloxide-semiconductor light-emitting devices Blue and red electroluminescence of Europium-implanted metal-oxide-semiconductor structures as a probe for the dynamics of microstructure Appl. Phys. Lett. 93, 071908 (2008); 10.1063/1.2964176 Switchable two-color electroluminescence based on a Si metal-oxide-semiconductor structure doped with Eu Appl. Phys. Lett. 90, 181121 (2007); 10.1063/1.2735285Bright green electroluminescence from Tb 3 + in silicon metal-oxide-semiconductor devicesThe anomalous wear-out phenomena of Eu-implanted metal-oxide-semiconductor devices were investigated. It will be shown that in contrast to other rare earth elements the electroluminescence ͑EL͒ intensity of Eu-implanted SiO 2 layers can rise under constant current injection before the known EL quenching will start. Under certain circumstances, this rise may amount up to two orders of magnitude. The EL behavior will be correlated with the microstructural and electrical properties of the devices. Transmission electron microscopy and Rutherford backscattering spectroscopy were applied to trace the development of Eu/Eu oxide clusters and the diffusion of Eu to the interfaces of the gate oxide layer. The hydrogen profile within the SiO 2 -SiON interface region was determined by nuclear reaction analysis. Current-voltage characteristics, EL decay times, and the progression of the voltage and the EL spectrum with increasing charge injection were measured to study charge and trapping phenomena in the oxide layer to reveal details of the EL excitation mechanism. A first qualitative model for the anomalous life time behavior is proposed.

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