The erbium-impurity interaction and its effects on the 1.54 μm luminescence of Er3+ in crystalline silicon

Abstract

We have studied the effect of erbium-impurity interactions on the 1.54 μm luminescence of Er3+ in crystalline Si. Float-zone and Czochralski-grown (100) oriented Si wafers were implanted with Er at a total dose of ∼1×1015/cm2. Some samples were also coimplanted with O, C, and F to realize uniform concentrations (up to 1020/cm3) of these impurities in the Er-doped region. Samples were analyzed by photoluminescence spectroscopy (PL) and electron paramagnetic resonance (EPR). Deep-level transient spectroscopy (DLTS) was also performed on p-n diodes implanted with Er at a dose of 6×1011/cm2 and codoped with impurities at a constant concentration of 1×1018/cm3. It was found that impurity codoping reduces the temperature quenching of the PL yield and that this reduction is more marked when the impurity concentration is increased. An EPR spectrum of sharp, anisotropic, lines is obtained for the sample codoped with 1020 O/cm3 but no clear EPR signal is observed without this codoping. The spectrum for the magnetic field B parallel to the [100] direction is similar to that expected for Er3+ in an approximately octahedral crystal field. DLTS analyses confirmed the formation of new Er3+ sites in the presence of the codoping impurities. In particular, a reduction in the density of the deepest levels has been observed and an impurity+Er-related level at ∼0.15 eV below the conduction band has been identified. This level is present in Er+O-, Er+F-, and Er+C-doped Si samples while it is not observed in samples solely doped with Er or with the codoping impurity only. We suggest that this new level causes efficient excitation of Er through the recombination of e-h pairs bound to this level. Temperature quenching is ascribed to the thermalization of bound electrons to the conduction band. We show that the attainment of well-defined impurity-related luminescent Er centers is responsible for both the luminescence enhancement at low temperatures and for the reduction of the temperature quenching of the luminescence. A quantitative model for the excitation and deexcitation processes of Er in Si is also proposed and shows good agreement with the experimental results.

Electron paramagnetic resonance and photoluminescence study of Er-impurity complexes in Si

“…The temperature dependence of the PL intensity from the two samples has also been studied. 13 Whilst the intensity of the 1.537-m peak in sample O1 at 15 K is approximately a factor of 3 stronger compared to that of sample O2, at RT the corresponding signal is the same in the two samples. As can be seen from Fig.…”

“…Coimplantation with either O or F has been shown to help in suppressing precipitation and Er concentrations as high as of 1ϫ10 19 /cm 3 have been incorporated in a goodquality Si single crystal by ion implantation. 6,13 These beneficial effects have been attributed to modifications in the local environment of the Er atom through the formation of Er-impurity complexes. [14][15][16] It is therefore of great interest to determine the structure of these complexes.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The 4f electrons are shielded from the full effects of the host crystal field and this results in the intra-4f shell optical transitions being both sharp and nearly independent of the host material. Furthermore, due to the close proximity of the 4f electrons to the nucleus, these electrons experience a strong spin-orbit interaction.…”

Crystal field analysis of Dy and Tm implanted silicon for photonic and quantum technologies

“…Extended X-ray absorption fine structure (EXAFS) measurements of Er-implanted, high O impurity Czochralski-grown Si, which exhibit strong PL at 1.54 µm, show Er is six-fold coordinated to oxygen [8]. Strong PL can also be observed from Er and O coimplanted Si [9]. By contrast, in low O impurity FZ Si, no PL was observed and Er was coordinated with 12 Si atoms [8].…”

“…In each case we overlapped PL spectra corresponding to transitions from multiple J manifolds to the ground state to reduce uncertainty in the position of energy levels in the ground state. For Dy 3+ (4f 9 ) the quantum numbers of the ground state are S = 5/2, L = 5 and J = 15/2, for Tm 3+ (4f 12 The PL spectra for Dy implanted Si in the 7000 to 7800 cm −1 region contains a mixture of 6 H 9/2 → 6 H 15/2 and 6 F 11/2 → 6 H 15/2 transitions [3], which is caused by overlapping of the 6 H 9/2 and 6 F 11/2 manifolds [25]. This makes determination of the ground state splitting difficult, however, the 5300 to 5900 cm −1 region contains only the 6 H 11/2 → 6 H 15/2 transition, which allows the ground state splitting to be discerned.…”