The optical properties of luminescence centres in silicon

We addressed the carrier dynamics in so-called G-centers in silicon (consisting of substitutional-interstitial carbon pairs interacting with interstitial silicons) obtained via ion implantation into a silicon-on-insulator wafer. For this point defect in silicon emitting in the telecommunication wavelength range, we unravel the recombination dynamics by time-resolved photoluminescence spectroscopy. More specifically, we performed detailed photoluminescence experiments as a function of excitation energy, incident power, irradiation fluence and temperature in order to study the impact of radiative and non-radiative recombination channels on the spectrum, yield and lifetime of G-centers. The sharp line emitting at 969 meV ($\sim$1280 nm) and the broad asymmetric sideband developing at lower energy share the same recombination dynamics as shown by time-resolved experiments performed selectively on each spectral component. This feature accounts for the common origin of the two emission bands which are unambiguously attributed to the zero-phonon line and to the corresponding phonon sideband. In the framework of the Huang-Rhys theory with non-perturbative calculations, we reach an estimation of 1.6$\pm$0.1 $\angstrom$ for the spatial extension of the electronic wave function in the G-center. The radiative recombination time measured at low temperature lies in the 6 ns-range. The estimation of both radiative and non-radiative recombination rates as a function of temperature further demonstrate a constant radiative lifetime. Finally, although G-centers are shallow levels in silicon, we find a value of the Debye-Waller factor comparable to deep levels in wide-bandgap materials. Our results point out the potential of G-centers as a solid-state light source to be integrated into opto-electronic devices within a common silicon platform.

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Optical properties of an ensemble of G-centers in silicon

Carbon and oxygen isotope effects in the 0.79 eV defect photoluminescence spectrum in irradiated silicon

The paper is concerned with recent photoluminescence (PL) data on irradiation induced defects and transition metal complexes. As for the former species, we discuss briefly three systems in the light of new high resolution measurements: The 0.97 eV (G) line, the 1.080 eV (I2) line and the 1.108 eV (J) multiple lines. A number of lately detected line systems have been ascribed to complexes containing transition ions. We shall discuss the identifications which were advanced in terms of Cu-Cu, Fe-B, Fe-In, Fe-Tl and Cr-B pairs, and on the basis of level schemes which are derived from the diverse PL techniques show that particle binding energies from PL can be related with DLTS levels for some complexes.

Photoluminescence characterization of deep defects in silicon

The optically active carbon related G-center is attracting great interest because of evidence that it can provide lasing in silicon. Here a technique to form the G-center in silicon is reported. The carbon G-center is generated by implantation of carbon followed by proton irradiation. Photoluminescence measurements confirm the controlled formation of high levels of the G-center that, importantly, completely dominates the emission spectrum. Unlike previous methods of introducing the G-center the current approach significantly is truly fully compatible with standard silicon ULSI (ultralarge scale integration) technology.

Co‐Implantation of Carbon and Protons: An Integrated Silicon Device Technology Compatible Method to Generate the Lasing G‐Center

We report on a high-resolution photoluminescence and absorption study with the application of external stress and magnetic fields on the 0.97-eV ($G$) line. We determine the symmetry of the related center to be monoclinic $I$. It is shown that satellite lines $E$, ${E}^{\ensuremath{'}}$, and ${E}^{*}$, which are observed in luminescence or absorption, are local modes of the $G$-line center. The low-energy local modes $E$ and ${E}^{\ensuremath{'}}$ both exhibit isotope effects upon $^{13}\mathrm{C}$ implantation of the Si samples. The doublet structure due to $^{12}\mathrm{C}$ and $^{13}\mathrm{C}$ gives evidence that one substitutional carbon atom is incorporated in the complex. We observe a nonthermalizing and stress-independent triplet structure of the $G$ line in luminescence as well as in absorption with intensities almost identical to the natural abundances of $^{28}\mathrm{Si}$, $^{29}\mathrm{Si}$, and $^{30}\mathrm{Si}$. This establishes our basic model of substitutional carbon atom interacting with a single silicon atom, ${\mathrm{Si}}^{*}$, in a prominent position. Relaxation of the complex leads to a symmetry lowering from a trigonal $〈111〉$ defect configuration to a monoclinic $I({C}_{1h})$ symmetry with a (110) mirror plane. Two particular models are discussed in detail, one being a ${\mathrm{C}}_{S}\ensuremath{-}{\mathrm{Si}}_{I}$ dumbbell having relaxed off a bond-centered $〈111〉$ position, the other being a carbon-vacancy complex similar to the electron-paramagnetic-resonance $\mathrm{S}\mathrm{i}\ensuremath{-}E$ center.

H. Klemisch

Papers

New model of the irradiation-induced 0.97-eV (G) line in silicon: A C S -Si * complex