1,721,257 research outputs found
Auger quenching-based modulation of electroluminescence from ion-implanted silicon nanocrystals
Full text linkWe describe high-speed control of light from silicon nanocrystals under electrical excitation. The nanocrystals are fabricated by the ion implantation of Si+ in the 15?nm thick gate oxide of a field effect transistor at 6.5?keV. A characteristic read-peaked electroluminescence is obtained either by DC or AC gate excitation. However, AC gate excitation is found to have a frequency response that is limited by the radiative lifetimes of silicon nanocrystals, which makes impossible the direct modulation of light beyond 100?kb?s?1 rates. As a solution, we demonstrate that combined DC gate excitation along with an AC channel hot electron injection of electrons into the nanocrystals may be used to obtain a 100% deep modulation at rates of 200?Mb?s?1 and low modulating voltages. This approach may find applications in biological sensing integrated into CMOS, single-photon emitters or direct encoding of information into light from Si-nc doped with erbium systems, which exhibit net optical gain. In this respect, the main advantage compared to conventional electro-optical modulators based on plasma dispersion effects is the low power consumption (104 times smaller) and thus the inherent large scale of integration. A detailed electrical characterization is also given. An Si/SiO2 barrier change from ?b = 3.2 to 4.2?eV is found while the injection mechanism is changed from Fowler?Nordheim to channel hot electron, which is a clear signature of nanocrystal charging and subsequent electroluminescence quenching
Optical and structural investigation on the energy transfer in a multicomponent glass co-doped with Si nanoaggregates and Er3+ ions
No full textEr site in Er-implanted Si nanoclusters embedded in SiO2
No full textWe have investigated by extended x-ray absorption fine structure spectroscopy the local order around Er atoms introduced by ion implantation in substoichiometric silica films prepared by plasma enhanced chemical vapor deposition, where Si nanoclusters have been formed by different preimplantation annealing processes. The results show that Er atoms are surrounded by a first shell of O atoms and no Er-Si direct correlations are observed; moreover, while the variation of the preimplantation annealing temperature has no effect on the Er site, it is observed that the increase of the Er concentration determines an increase of both the Er first shell coordination number and the Er-O interatomic distance, becoming more similar to those of Er2O3. In the presence of an extensive phase separation between Si and SiO2 the local environment around Er plays a crucial role on the efficiency of the photoluminescence emission at 1.54 mu m, which is significantly increased when the first shell of atoms around Er is closer to that one of Er2O3
Plasma processing: a novel method to reduce the transient enhanced diffusion of boron implanted in silicon
No full textIn this paper a novel method is presented, based on the use of plasma processing, to suppress the transient enhanced diffusion of boron implanted in silicon. We found for silicon samples processed with plasma and subsequently boron implanted that the anomalous diffusion of the dopant atoms at the beginning of the annealing process is almost completely suppressed. This phenomenon is interpreted in terms of capture of the ion beam generated interstitials by the dislocations induced by the plasma processing. At room temperature the dislocations are observed to grow in size after the boron implant, attesting their efficiency as trapping centres for interstitials. Moreover, varying the plasma process conditions we can establish a general relation between the presence of the trapping centres induced by the plasma processing and the suppression of the transient diffusion. (C) 1999 Elsevier Science B.V. All rights reserved
Clustering of ultra-low-energy implanted Boron in Silicon during postimplantation annealing
No full textActivation annealing of ultra-low-energy implanted boron in silicon: a study combining experiment and process modeling
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The effect of the impurity content and of the surface on the electrical activation of low energy implanted boron in crystalline Si
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