Chapter 4 Erbium in Silicon

Michel, Jürgen; Assali, L. V. C.; Morse, Mike; Kimerling, Lionel C.

doi:10.1016/s0080-8784(08)62502-8

Cited by 28 publications

(11 citation statements)

References 73 publications

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“…Depending on how strong the bonding and interaction of Er 3ϩ with its surroundings is, the resulting energy of the Er 4 f levels ranges from far below the band gap ͑ϳ20 eV͒ to a position directly in the band gap of c-Si. 58,[72][73][74][75] As far as amorphous silicon is concerned, recent experimental results by Tessler et al, 76 using ultraviolet photoemission spectroscopy ͑UPS͒ on a-Si:H͑Er͒ samples, found a binding energy E B , attributed to the Er 3ϩ 4 f levels, which is roughly 10 eV below the Si valence-band maximum. This feature in the UPS spectra, however, could only be seen as a rather weak peak at high excitation photon energy ͑140 eV͒.…”

Section: Discussionmentioning

confidence: 99%

Photoluminescence ofEr3+-implanted amorphous hydrogenated silicon suboxides

et al. 2003

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Erbium ions incorporated into amorphous hydrogenated silicon suboxides (a-SiO x :H) allow to overcome the disadvantages of Er 3ϩ in c-Si such as the limited solubility, the strong quenching of the luminescence at room temperature, and the need for co-doping with electronegative atoms. a-SiO x :H alloys have an enhanced Er solubility and easily variable oxygen content, thereby providing favorable atomic environments for an efficient Er luminescence and reduced excitation backtransfer due to deeper localized band-tail states. In the present study, Er 3ϩ doses up to 7ϫ10 14 cm Ϫ2 were implanted into a-SiO x :H with oxygen content between 0 and 44 at. %. Optical properties such as the absorption coefficients and the photoluminescence ͑PL͒ spectra of the Er 3ϩ ions and of the SiO x host were investigated as a function of erbium implantation dose, oxygen content, defect density, temperature, and annealing treatment. It was found that annealing is a requirement for activating the characteristic Er PL at 1.54 m mainly due to a reduction of implantation induced defects. The intensity of both the intrinsic SiO x and the Er PL was found to be inversely proportional to the defect density as measured by electron spin resonance or subgap absorption. The Er PL is additionally enhanced upon annealing, probably as a result of better structural arrangements of the Er ions. The Er PL intensity increases approximately linearly with the implantation dose. An increase of the oxygen content ͑and correspondingly of the optical band gap͒ of a-SiO x :H causes no drastic changes in the erbium luminescence energy and intensity, whereas the intrinsic PL shifts to higher photon energies according to the larger band gap. Already low O concentrations of a few percent provide favorable Er environments. The main advantage of a-SiO x :H as a host matrix is revealed by temperature-dependent PL measurements. For high oxygen contents, the thermal quenching of both the Er 3ϩ and the intrinsic PL is strongly reduced. In an a-SiO x sample with 44 at. % oxygen, the Er PL is only quenched by 20% between 77 and 300 K. In contrast, the quenching of the intrinsic PL for all ͓O͔ is roughly one order of magnitude stronger than that of the Er PL. These PL measurements were complemented by PL excitation experiments over a wide spectral range. We have observed that the Er 3ϩ PL is excited about one order of magnitude more efficiently when pumped with sub-band-gap light compared to band-toband excitation. The experimental results are discussed with regard to the two currently proposed Er 3ϩ excitation models, the defect-related Auger effect and the Förster transfer mechanism.

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Section: Discussionmentioning

confidence: 99%

Photoluminescence ofEr3+-implanted amorphous hydrogenated silicon suboxides

et al. 2003

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“…Erbium is of interest because of the 4 I 13=2 ! 4 I 15=2 ligand field transition and the resulting luminescence band at 1:54 m which lies at an absorption minimum for silica based optical fibers and glasses [5,6]. A Si-based nanoscale light emitter whose luminescence originates from Si exciton-mediated energy transfer with rare earth centers such as Er 3 could prove useful for the construction of a monolithic Si-based optoelectronic device.…”

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Structural Influence of Erbium Centers on Silicon Nanocrystal Phase Transitions

et al. 2004

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Two different types of erbium-doped silicon nanocrystals, along with undoped, oxide-capped Si dots, are employed to probe the impact of the impurity center location on phase transition pressure. Using a combination of high pressure optical absorption, micro-Raman, and x-ray diffraction measurements in a diamond anvil cell, it is demonstrated that the magnitude of this phase transition elevation is strongly dictated by the average spatial location of impurity centers introduced into the nanocrystal along with the interfacial quality of the surrounding oxide.

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“…It is known that a certain amount of Er doped onto the surface of Ge nanowires can improve their optical properties, since the luminescence band at 1.54 μm, induced from the 4 I 13/2 → 4 I 15/2 transition of Er ions, lies at an absorption minimum for semiconducting element-based optical waveguides. , Also, given that a clear understanding of the physical properties, including phase relation, elasticity, and vibrational properties, is an essential prerequisite for the practical application of a material, we combine here the high-pressure technique (via a diamond anvil cell) with Raman spectroscopy and high-energy synchrotron XRD to investigate Ge nanowires with and without surface Er doping. The experimental data allows us to address the surface Er doping effects on the thermodynamic, vibrational, and mechanical behavior of Ge nanowires under high pressure.…”

Section: Introductionmentioning

confidence: 99%

Anomalous Surface Doping Effect in Semiconductor Nanowires

et al. 2017

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Surface doping is being used as an effective approach to improve the mechanical, optical, electronic, and magnetic properties of various materials. For example, experimental studies have proven that rare-earth element doping can enhance the optical properties of silicon nanostructures. However, the majority of previous investigations focused on either bulk materials or nanosized spherical crystals. Here we present a comparative study on semiconducting germanium (Ge) nanowires with and without surface doping by using multiple integrated characterization probes, including high resolution scanning/transmission electron microscopy (SEM/TEM), in situ high pressure synchrotron X-ray diffraction (XRD), and Raman spectroscopy. Our results reveal that under pressure the stability of the Ge-I phase (diamond structure) in erbium (Er)-doped Ge nanowires is enhanced compared to undoped Ge nanowires. We also found an increased stability of the Ge-II phase (body centered tetragonal structure) in Er-doped Ge nanowires during decompression. Furthermore, the presence of Er doping elevates the transition kinetics by showing a smaller pressure span needed for a complete Ge-I to Ge-II phase transformation. In contrast, Er doping has a negligible impact on the mechanical properties of Ge nanowires under high pressure, exhibiting a very different mechanical behavior from other foreign element-doped nanostructures. This anomalous doping effect was explained based on surface modification and decoration. These findings are of both fundamental and applied significance, because they not only provide a thorough understanding of the distinct role of surface doping in nanoscale materials, but also yield insight with regard to a given material’s design for favorable properties in semiconductor nanostructures.

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Chapter 4 Erbium in Silicon

Cited by 28 publications

References 73 publications

Photoluminescence ofEr3+-implanted amorphous hydrogenated silicon suboxides

Photoluminescence ofEr3+-implanted amorphous hydrogenated silicon suboxides

Structural Influence of Erbium Centers on Silicon Nanocrystal Phase Transitions

Anomalous Surface Doping Effect in Semiconductor Nanowires

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