V.S. Lysenko

Semiconductor-on-insulator materials for nanoelectronics applications

New semiconductor-on-insulator materials.- Physics of modern SemOI devices.- Diagnostics of the SOI devices.- Sensors and MEMS on SOI.

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.

The effect of rare-earth clustering on charge trapping and electroluminescence in rare-earth implanted metal-oxide-semiconductor light-emitting devices

The effect of rare-earth clustering in dielectric media on the electroluminescence (EL) intensity, the charge trapping and the EL quenching was investigated using the example of Tb and Eu-implanted SiO2 layers. It was shown that the increase in the REOX cluster size induced by an increase in the furnace annealing temperature resulted in an increase in the concentration of electron traps with capture cross sections from 2×10−15 to 2×10−18 cm2. This is probably associated with an increase in the concentration of oxygen deficiency centers as well as with strained and dangling bonds in the SiO2 matrix which leads to an enhanced scattering of hot electrons and a decrease in the excitation cross section of the main EL lines of RE3+ ions. For the main EL lines of Tb3+ and Eu3+ ions the relation of the EL quenching to negative and positive charge generation in the SiO2 was considered. It was demonstrated that in case of REOX nanoclusters with small sizes (up to 5 nm) the EL quenching process can mainly be explain...

Structure, paramagnetic defects and light-emission of carbon-rich a-SiC:H films

The effect of vacuum annealing on local structure reconstruction, evolution of photoluminescence (PL) and paramagnetic defects in carbon-rich a-Si1−xCx:H films (x=0.7) was studied. Strong enhancement of visible (white-green) PL was observed after annealing in the temperature range of 400–500 °C. Such enhancement was correlated with increasing of the concentration of carbon-hydrogen bonds in Si:CHn accompanied with increase in the fluctuation of the interatomic potential. Complete disappearance of PL, “graphitization” of the carbon precipitates, and a strong increase in the concentration of the paramagnetic states were observed after annealing at 650 °C and above. The enhancement and the degradation of PL after different-temperature treatments are explained by the following competing effects: (1) enhancement of the radiative recombination due to passivation of paramagnetic defects with hydrogen and increase of localization of photoexcited electron-hole pairs due to formation of new Si:CH and (2) enhancem...

Effect of oxide–semiconductor interface traps on low-temperature operation of MOSFETs

Abstract Operation of n-channel MOSFET was studied at low temperatures. It has been shown that the charge state of shallow traps in the Si/SiO 2 interface is responsible for the hysteresis of transistor drain characteristics in the prekink region. Thermally activated emptying of these traps leads to the sharp decrease of the current in the subthreshold mode of transistor operation.

Border traps in 6H-SiC metal–oxide–semiconductor capacitors investigated by the thermally-stimulated current technique

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.

Effects of hydrogen bond redistribution on photoluminescence of a-SiC:H films under thermal treatment

Hydrogenated amorphous silicon carbide (a-SiC:H) films have been deposited using magnetron sputtering technique. An integrated investigation of the effect of vacuum annealing temperature on photoluminescence properties and paramagnetic defects and its correlation with structural transformation of a-SiC:H has been performed. Significantly enhanced light emission efficiency after low-temperature vacuum treatment (450°C) is found due to enhanced passivation of paramagnetic defects associated with carbon-rich chemically disordered structure. Subsequent high-temperature vacuum annealing results in a decrease of luminescent intensity that is associated with an increase of carbon-related paramagnetic defect states, shown to be the primary nonradiative recombination centers.

Effect of traps in the transition Si/SiO2 layer on input characteristics of SOI transistors

Abstract In this article, investigations of low-temperature operation of n-channel accumulation mode SOI MOSFET are reported. It has been shown that the charge state of shallow traps situated in the thin transition layer between the gate oxide and silicon overlayer affects the transistor characteristics at temperatures below 20 K, giving rise to peaks in transconductance.