Self-organization of germanium nanoislands obtained in silicon by molecular-beam epitaxy

Aleshkin, V. Ya.; Bekin, N. A.; Kalugin, Nikolai G.; Krasilnik, Z. F.; Новиков, А. В.; Postnikov, V. V.; Seyringer, Heinz

doi:10.1134/1.567626

Cited by 34 publications

(6 citation statements)

References 6 publications

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“…Room‐temperature photoluminescence (PL) is observed in such structures at wavelengths 1.3–1.6 µm (0.75–0.95 eV). However, due to the spatial separation of holes and electrons in Ge nanoislands, [ 33 ] their radiative recombination efficiency is not high enough for practical applications. There are several approaches for the increase of this efficiency among which may be mentioned a vertical arrangement of nanoislands in a lattice [ 34 ] and ion bombarding of Ge nanoislands.…”

Section: Introductionmentioning

confidence: 99%

Photonic Bound States in the Continuum in Si Structures with the Self‐Assembled Ge Nanoislands

Dyakov

Stepikhova

Bogdanov

et al. 2021

Laser & Photonics Reviews

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Germanium self-assembled nanoislands and quantum dots are very prospective for CMOS-compatible optoelectronic integrated circuits but their photoluminescence (PL) intensity is still insufficient for many practical applications. Here, it is demonstrated experimentally that the PL of Ge nanoislands in silicon photonic crystal slabs (PCS) with hexagonal lattice can be dramatically enhanced due to the involvement in the emission process of the bounds states in the continuum. These high-Q photonic resonances allow to achieve PL resonant peaks with the quality factor as high as 2200 and with the peak PL enhancement factor of more than two orders of magnitude. The corresponding integrated PL enhancement is demonstrated to be more than one order of magnitude. This effect is studied theoretically by the Fourier modal method in the scattering matrix form. The symmetry of the quasi-normal guided modes in the PCS is described in terms of group theory. This work paves the way toward a new class of optoelectronic components compatible with silicon technology.

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Section: Introductionmentioning

confidence: 99%

Photonic Bound States in the Continuum in Si Structures with the Self‐Assembled Ge Nanoislands

Dyakov

Stepikhova

Bogdanov

et al. 2021

Laser & Photonics Reviews

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“…In the PL spectra measured using the micro-PL setup, the as-grown sample demonstrated relatively weak signals related to Si band edge transitions in the energy range of 1050 ÷ 1150 meV as well as signals related to the different optical transitions in Ge(Si) nanoislands in the energy range of 750 ÷ 950 meV ( Figure 3 a) [ 44 , 45 , 50 ]. The shape of these signals from the as-grown sample is significantly affected by the interference effects caused by multireflection from the buried oxide layer of the SOI substrate.…”

Section: Resultsmentioning

confidence: 99%

Interaction of Ge(Si) Self-Assembled Nanoislands with Different Modes of Two-Dimensional Photonic Crystal

et al. 2022

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The interaction of Ge(Si)/SOI self-assembled nanoislands with modes of photonic crystal slabs (PCS) with a hexagonal lattice is studied in detail. Appropriate selection of the PCS parameters and conditions for collecting the photoluminescence (PL) signal allowed to distinguish the PCS modes of different physical nature, particularly the radiative modes and modes associated to the bound states in the continuum (BIC). It is shown that the radiative modes with relatively low Q-factors could provide a increase greater than an order of magnitude in the integrated PL intensity in the wavelength range of 1.3–1.55 µm compared to the area outside of PCS at room temperature. At the same time, the interaction of Ge(Si) islands emission with the BIC-related modes provides the peak PL intensity increase of more than two orders of magnitude. The experimentally measured Q-factor of the PL line associated with the symmetry-protected BIC mode reaches the value of 2600.

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“…Figure 5 shows a PL spectrum measured at 4 K. Apart from the Si-related PL lines (all peaks with an energy above 1050 meV and the TO + O phonon-assisted transition at 1028 meV (sharp peak)) due to the Si substrate and capping layer we can identify two PL peaks from the wetting layer (NP WL , a broad peak with a maximum around 1030 meV, and TO WL , an assisted peak at 980 meV) and two PL peaks at lower energies related to GeSi islands (852 and 805 meV). We associate the low energy PL peaks with non-phonon (NP isl ) and phonon assisted (TO isl ) real-space indirect optical transitions between the heavy holes confined in GeSi islands and the electrons located in Si on the heterojunction of the island [18] (see inset in figure 5).…”

Section: Resultsmentioning

confidence: 99%

The effect of local atomic structure on the optical properties of GeSi self-assembled islands buried in silicon matrix

et al. 2007

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The local atomic structure of GeSi self-assembled islands buried in a silicon matrix strongly influences the optical properties of such systems. In the present paper this structure was determined by x-ray absorption fine-structure (XAFS) spectroscopy and high resolution transmission electron microscopy (HRTEM) and used to build a schematic description of the band structure model. Quantitative analysis of the extended XAFS (EXAFS) spectrum was performed for three coordination shells around the Ge absorbing atom with multiple scattering taken into account. It was proved that the coordination number of elements in an alloy resulting from EXAFS analysis for all three coordination spheres (i.e. ‘mixing degree’ parameters) cannot be taken as the concentration of alloy but can be used together with a proper model of the alloy unit cell to calculate a realistic concentration. The fraction of Ge calculated in this way is consistent with HRTEM results. The found model of the unit cell was used to generate a x-ray absorption near edge structure spectrum by ab initio calculations. This approach yielded a spectrum in good agreement with the experimental one. The information gained from XAFS and HRTEM was then used for calculation of the band structure diagram. Results of the calculation are discussed and compared with the experimental photoluminescence spectrum.

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Self-organization of germanium nanoislands obtained in silicon by molecular-beam epitaxy

Cited by 34 publications

References 6 publications

Photonic Bound States in the Continuum in Si Structures with the Self‐Assembled Ge Nanoislands

Photonic Bound States in the Continuum in Si Structures with the Self‐Assembled Ge Nanoislands

Interaction of Ge(Si) Self-Assembled Nanoislands with Different Modes of Two-Dimensional Photonic Crystal

The effect of local atomic structure on the optical properties of GeSi self-assembled islands buried in silicon matrix

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