I.N. Osiyuk

Light emission and charge trapping in Er-doped silicon dioxide films containing silicon nanocrystals

The processes of electro- (EL) and photoluminescence (PL) and charge trapping in Er-implanted SiO2 containing silicon nanoclusters have been studied. It is shown that in Er-doped SiO2 with an excess of silicon nanoclusters of 10 at. %, a strong energy transfer from silicon nanoclusters results in a ten-fold increase of the PL peak at 1540 nm from Er luminescent centers, whereas the EL is strongly quenched by the excess silicon nanoclusters. It is further shown that the implantation of Er creates in the oxide positive charge traps with a giant cross section (σh0>10−13cm2). Introducing subsequent silicon nanocrystals in the oxide leads to the formation of negative charge traps of a giant cross section (σe0>10−13cm2). The possible reason for the EL quenching in the Er-doped SiO2 by silicon nanoclusters is discussed.

Trapping of negative and positive charges in Ge+ ion implanted silicon dioxide layers subjected to high-field electron injection

Negative and positive charge trapping in a constant current regime under high-field electron injection both from Al electrode and Si substrate in high-dose Ge+ ion implanted and then rapid thermal annealed thin-film dioxide has been studied. Negatively charged traps as well as generated positive charges with effective capture cross sections of σ1(−)>10−14 cm2, σ2(−)≈1.8×10−15, σ3(−)≈2×10−16, and σ4(−)≈3×10−18 cm2, as well as σ1(+)≈(5–7)×10−15 and σ2(+)≈3.3×10−16 cm2, respectively, are shown to be introduced into the oxide layer. A good correlation of the electron trap concentration with a cross section of σ1(−)>10−14 cm2 and the concentration of the implanted Ge atoms, determined by Rutherford backscattering spectrometry inside the oxide, is observed. The decrease of Ge concentration within the oxide layer with increasing duration of rapid thermal annealing is associated with Ge atom outdiffusion from the oxide at high-temperature annealing. The generated positive charge is shown to be collected near the ...

Charge trapping in light-emitting SiO2 layers implanted with Ge+ ions

The trapping effects of negative and positive charge in Ge-enriched SiO2 layers during high-field electron injection from the Si substrate of Al–SiO2–Si structures are studied. The capture cross section and the concentration of negatively and positively charged traps are estimated and the location of the positively charged traps is determined. It is shown that increasing rapid thermal annealing time from 6 to 150 s at 1000 °C leads to an enhanced diffusion of Ge towards the SiO2–Si interface and an increase in negatively and positively charged trap concentration. The mechanisms of the trap generation are discussed.

Correlation of charge trapping and electroluminescence in highly efficient Si-based light emitters

Abstract In this paper we report on recent results on charge trapping and electroluminescence (EL) from Ge rich SiO2 layers. Thermally grown 80 nm thick SiO2 layers were implanted with Ge ions at energies of 30– 50 keV to peak concentrations of 1– 6 at %. Subsequently rapid thermal annealing was performed at 1000°C for 6, 30 and 150 s under a nitrogen atmosphere in order to form luminescence centers. A combination of capacitance–voltage (CV) and current–voltage (IV) methods was used for the investigation of the trapping properties. It was found that at electric fields MV / cm electron trapping dominates while at higher electric fields which are typically required for the EL operation of the devices positive charge trapping occurs. It is assumed, that the trapping sites which are responsible for the trapping of the positive charge are in strong relation to the defects causing the luminescence.

Rare earth ion implantation for silicon based light emission

Using ion implantation different rare earth luminescent centers (Gd3+, Tb3+, Eu3+, Ce3+, Tm3+, Er3+) were formed in the silicon dioxide layer of a purpose-designed Metal Oxide Silicon (MOS) capacitor with advanced electrical performance, further called a MOS-light emitting device (MOSLED). Efficient electroluminescence was obtained for the wavelength range from UV to infrared with a transparent top electrode made of indium-tin oxide. Top values of the efficiency of 0.3 % corresponding to external quantum efficiencies distinctly above the percent range were reached. The electrical properties of these devices such as current-voltage and charge trapping characteristics, were also evaluated. Finally, application aspects to the field of biosensing will be shown.

Comparative Study of Charge Trapping in High-Dose Si and Ge-Implanted Al / SiO2 / Si Structures

We have studied the trapping of negative and positive charge in Si-implanted SiO 2 layers of Al/SiO 2 /Si-based devices during high-field electron injection from the Si substrate under conditions typically used for obtaining electroluminescence. The location, capture cross section, and concentration of negatively and positively charged traps are determined in dependence on the time of heat-treatment by rapid thermal annealing (RTA). A comparison between the results obtained from Si- and Ge-implanted oxide layers is made. It is shown that in the case of Si-rich oxides an increase in the RTA time leads to the formation of hole and electron traps of high concentration, both of which are located within the oxide. For Ge-rich oxide layers, however, the hole traps are found primarily in the vicinity of the SiO 2 /Si interface while the electron traps are present within the oxide. The nature of these traps is discussed.