H. Fröb

Strong blue and violet photoluminescence and electroluminescence from germanium-implanted and silicon-implanted silicon-dioxide layers

The photoluminescence (PL) and electroluminescence (EL) properties of Ge-implanted SiO2 layers thermally grown on a Si substrate were investigated and compared to those of Si-implanted SiO2 films. The PL spectra from Ge-implanted SiO2 were recorded as a function of annealing temperature. It was found that the blue-violet PL from Ge-rich oxide layers reaches a maximum after annealing at 500 °C for 30 min, and is substantially more intense than the PL emission from Si-implanted oxides. The neutral oxygen vacancy is believed to be responsible for the observed luminescence. The EL spectrum from the Ge-implanted oxide after annealing at 1000 °C correlates very well with the PL one, and shows a linear dependence on the injected current. The EL emission was strong enough to be readily seen with the naked eye and the EL efficiency was assessed to be about 5×10−4.

Strong photoluminescence of Sn-implanted thermally grown SiO2 layers

The photoluminescence (PL) and PL excitation (PLE) properties of Sn-implanted SiO2 layers thermally grown on crystalline Si have been investigated and compared with those from Ge- and Si-implanted SiO2 layers. In detail, the violet PL of Sn-implanted SiO2 layers is approximately two and 20 times higher than those of Ge- and Si-implanted SiO2 layers, respectively. Based on PL, PLE, and decay time measurements, the violet PL is interpreted as due to a triplet–singlet transition of the neutral oxygen vacancy typical for Si-rich SiO2 and similar Ge- and Sn-related defects in Ge- and Sn-implanted SiO2 films. The enhancement of the blue–violet PL within the isoelectronic row of Si, Ge, and Sn is explained by means of the heavy atom effect.The photoluminescence (PL) and PL excitation (PLE) properties of Sn-implanted SiO2 layers thermally grown on crystalline Si have been investigated and compared with those from Ge- and Si-implanted SiO2 layers. In detail, the violet PL of Sn-implanted SiO2 layers is approximately two and 20 times higher than those of Ge- and Si-implanted SiO2 layers, respectively. Based on PL, PLE, and decay time measurements, the violet PL is interpreted as due to a triplet–singlet transition of the neutral oxygen vacancy typical for Si-rich SiO2 and similar Ge- and Sn-related defects in Ge- and Sn-implanted SiO2 films. The enhancement of the blue–violet PL within the isoelectronic row of Si, Ge, and Sn is explained by means of the heavy atom effect.

Ion beam processing for Si/C-rich thermally grown SiO2 layers: photoluminescence and microstructure

In this paper, the luminescence properties of thin, thermally grown SiO 2 layers implanted with silicon and carbon ions are explored. The doses and energies were chosen in such a way that the resulting peak concentration of excess Si and C amounts to 5-10% in a depth region of 60-180 nm below the surface. The microstructure was investigated by Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). Amorphous nanostructures with a size between 2 and 3.5 nm were found in depth region between 80 and 150 nm below the oxide surface. Strong photoluminescence (PL) around 2.1 and 2.7 eV has been observed after excitation at 4.77 eV. Si y C 1-y O x complexes with x < 2 are assumed to cause the observed PL in the blue spectral region.

Photoluminescence and electroluminescence investigations at Ge-rich SiO2 layers

Strong blue and violet photo (PL) and electroluminescence (EL) at room temperature was obtained from SiO 2 -films grown on crystalline Si, which were either single (SI) or double implanted (DI) with Ge ions and annealed at different temperatures. The PL spectra of Ge-rich layers reach a maximum after annealing at 500-700 C for DI layers or 900-1000°C for SI layers, respectively. Both, PL and EL of 500 nm thick Ge-rich layers are easily visible by the naked eye at ambient light due to their high intensity. Based on excitation spectra we tentatively interpret the blue PL as due to the oxygen vacancy in silicon dioxide. The EL spectrum of the Ge-implanted oxide correlates very well with the PL one and shows a linear dependence on the injected current over three orders of magnitude. For DI layer much higher injection currents than for SI layers can be achieved. An EL efficiency in the order of 10 -4 for Ge - -implanted silicon dioxide was determined.

Ion beam synthesized nanoclusters for silicon-based light emission

Abstract Strong blue and violet photoluminescence (PL) and electroluminescence (EL) at room temperature has been achieved from thin SiO 2 layers implanted with group IV elements. Thermally grown SiO 2 films with thicknesses between 130 and 500 nm were implanted with Si + , Ge + or Sn + ions followed by different annealing procedures. Based on PL and PL excitation spectra we tentatively interpret the blue–violet PL as due to a T 1 →S 0 transition of an oxygen deficiency center. The strong EL is well visible with the naked eye and reaches a power efficiency of up to 5×10 −3 for Ge. Whereas the EL intensity shows a linear dependence on the injection current for Ge-rich layers, the shape of the EL spectrum remains unchanged. It was found that the I – V characteristics shift to lower applied electric fields with increasing implantation fluence. Furthermore, it is assumed that the luminescence centers will be excited either by field ionization or by the scattering of hot electrons. Finally, the suitability of ion implanted silicon dioxide layers for optoelectronic applications is discussed.

A study of the blue photoluminescence emission from thermally-grown, Si+-implanted SiO2 films after short-time annealing

Abstract Thermal SiO 2 films have been implanted with Si + ions using double-energy implants (200 + 100 keV) at a substrate temperature of about −20°C to total doses in the range 1.6 × 10 16 −1.6 × 10 17 cm −2 followed by short-time thermal processing, in order to form a Si nanostructure capable of yielding blue photoluminescence (PL). The intensity and the peak position of the PL band have been investigated as a function of ion dose, manner of heat treatment, anneal time and anneal temperature. For the formation of blue PL emitting centres, optimum processing conditions in terms of excess Si concentration and overall thermal budget are mandatory. The nature of the observed blue emission is discussed.

Strong Blue and Violet Photo‐ and Electroluminescence from Ge‐ and Si‐Implanted Silicon Dioxide

The photoluminescence (PL) and electroluminescence (EL) properties of Ge-implanted SiO2 films thermally-grown on a Si substrate have been investigated and compared to those of Si-implanted SiO2 films. It is found that the blue-violet PL from both Si and Ge-rich layers reaches a maximum after annealing at 500 C for 30 min. The PL and EL from Ge-implanted SiO2 are distinctly higher than that from Si-implanted layers and well visible for the naked eye. The EL spectrum from the Ge-implanted oxide annealed at 1000 C correlates very well with the PL one and shows a linear dependence on the injected current. The neutral oxygen vacancy is assumed to be responsible for the observed luminescence. In the case of Ge the microstructure after high temperature annealing is studied.