No abstract

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.

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 SiO2/Si interface during the high field electron injection, both from the Al and Si side. A correlation of the generated positive charge with the Ge atoms embedded in the SiO2/Si interface is observed. The anode hole injection mechanism is suggested to be responsible for the observed generation of the positive charge.

Electrical conduction and electroluminescence in nanocrystalline silicon-based light emitting devices

No abstract

We demonstrate the usefulness of the thermally-stimulated current (TSC) technique for investigating shallow interface state defects in silicon carbide metal–oxide–semiconductor (MOS) structures. For dry oxides, low-temperature TSC measurements reveal a high density of near-interfacial oxide traps (border traps) close to the band edges of 6H–SiC. Furthermore we find that annealing the SiC/SiO2 interface in pyrogenic steam at 950 °C (reoxidation) essentially reduces the density of deep interface states, while it increases the density of shallow states. Our results agree with observations of the appearance of a negative oxide charge in reoxidized MOS capacitors and the corresponding increase of the threshold voltage in n channel metal–oxide–semiconductor field-effect transistors.

We study the 4H-SiC/SiO 2 interface by using thermally stimulated current (TSC) measurements and find an extremely high density of shallow traps near the conduction band edge at the SiC/SiO 2 interface (> 10 13 cm −2 ). The TSC spectra reveal two distinguishable peaks and using various charging temperatures we show that the charging mechanism for the traps responsible for the high-temperature TSC peak (at about 140 K) is thermally activated. Similar TSC spectra are observed in differently prepared thermal oxides.

No abstract