Hydrogen plasma treatment of silicon thin-film structures and nanostructured layers

The review concentrates on the analysis of the RF hydrogen plasma effect on thin-film metal-dioxide-silicon and silicon-dioxide silicon structures which are a modern basis of micro- and nanoelectronics. The especial attention is paid to athermic mechanisms of transformation of defects in dioxide, SiO₂-Si interface and SiO₂-Si nanocrystal ones and thin layers of silicon; atomic hydrogen influence on the annealing of vacancy defects and the implanted impurity activation in a subsurface implanted silicon layer; and the hydrogen plasma effect on luminescent properties of nanostructured light emitting materials

Influence of traps in gate oxide-Si film transition layers on FD MOSFET's characteristics at cryogenic emperatures

The results of experiments on the influence of recharging the electron traps in a Si-SiO₂ transition layer on the low-temperature characteristics of fully depleted silicon in insulator MOSFET devices are presented. It is shown that the low-dose gammaradiation improves electrophysical parameters of the transition layer

High-temperature characteristics of zone-melting recrystallized silicon-on-insulator MOSFETs

The characteristics of enhancement-mode MOS transistors fabricated on zone-melting recrystallized (ZMR) silicon-on-insulator (SOI) films were systematically experimentally investigated in the temperature range 25–300°C. The main temperature-dependent parameters (the threshold voltage, the channel mobility, subthreshold slope, off-state leakage currents) of ZMR SOI MOSFETs are described and compared with both theory and SIMOX devices. It is shown that high carrier mobilities and low off-state leakage currents can be obtained in thin-film ZMR SOI MOSFETs at elevated temperatures. At T = 300°C, far beyond the operating range of bulk silicon devices, the off-state leakage current in ZMR SOI MOSFETs with a 0.15 mm-thick silicon film was only 0.5 nA/mm (for VD = 3 V), that is 3–4 orders of magnitude lower than typical values in bulk Si devices. The presented results demonstrate that CMOS devices fabricated on sufficiently thin ZMR SOI films are well suited for high-temperature applications.Проведені кропіткі експериментальні дослідження високотемпературних (25-300°С) характеристик МОН транзисторів на базі КНІ-структур, виготовлених методом зонної лазерної перекристалізації. Розглянута поведінка основних температрно-залежних параметрів КНІ МОН транзисторів (порогової напруги, рухливості носіїв, підпорогового нахилу та струму витоку). Проведено порівняння отриманих результатів з теорією та аналогічними параметрами приладів, створених за допомогою ЗІМОХ технології. Показано, що при підвищених температурах тонкоплівкові транзистори, отримані лазерною зонною перекристалізацією, виявляють високу рухливість носіїв і низькі струми витоку закритого транзистора. При Т = 300°С, що значно перевищує робочий діапазон приладів на об.ємному кремнії, струм витоку в КНІ транзисторах з плівкою Si товщиною 0,15 мкм ст всього лишу 0,5 nA/mm (при VD = ЗВ), що на 3-4 порядка нижче типових величин для приладів на об.ємному кремнії. Наведені результати свідчать, що тонкі плівки КНІ, створені методом лазерної зонної перекристалізації, можуть успішно використовуватись для створення КМОН ІС для високотемпературних застосувань.Проведено детальное экспериментальное исследование высокотемпературных (25-300°С) характеристик МОП транзисторов на основе КНИ-структур, изготовленных методом лазерной зонной перекристаллизации. Рассмотрено поведение основных температурно-зависимых параметров КНИ МОП транзисторов (порогового напряжения, подвижности носителей, подпорогового наклона и тока утечки). Проведено сравнение полученных результатов с теорией и аналогичными параметрами приборов, созданных SIМОХ технологией. Показано, что при повышенных температурах тонкопленочные транзисторы, полученные лазерной зонной перекристаллизацией, проявляют высокую подвижность носителей и низкие токи утечки закрытого транзистора. При Т = 300°С, значительно превышающей рабочий диапазон приборов на объемном кремнии, ток утечки в КНИ транзисторах с пленкой Si толщиной 0,15 мкм составляет всего лишь 0,5 nA/mm (при VD = ЗВ), что на 3-4 порядка ниже типичных величин для приборов на объемном кремнии. Приведенные результаты свидетельствуют, что тонкие пленки КНИ, полученные методом лазерной зонной перекристаллизации, могут успешно использоваться для создания КМОП ИС для высокотемпературных применений

Characterization of charge trapping processes in fully-depleted UNIBOND SOI MOSFET subjected to γ-irradiation

An investigation of radiation effect on edgeless accumulation mode (AM) p-channel and fully-depleted enhancement mode (EM) n-channel MOSFETs, fabricated on UNIBOND silicon on insulatior wafers (SOI), is presented in the paper. Characterization of trapped charge in the gate and buried oxides of the devices was performed by measuring only the front-gate transistors. It was revealed that the irradiation effect on EM n-MOSFET is stronger than that on AM p-MOSFET. Radiation-induced positive charge in the buried oxide proved to invert back interface what causes back channel creation in EM n-MOSFET but no such effect in AM p-MOSFET has been not observed. The effect of improving the quality of both interfaces for small irradiation doses is demonstrated

Photoluminescent properties of oxidized stochiometric and carbon-rich amorphous Si₁₋xCx:H films

Near-stochiometric and carbon-rich a-Si₁₋xCx:H thin films were deposited using the magnetron sputtering of Si target in Ar/CH₄ gas mixture. As-deposited nearstochimetric (x = 0.5) sample showed weak blue photoluminescence (PL), while PL of as-deposited carbon-rich (x = 0.7) sample was 20 times stronger and white in color. The films were annealed in pure argon, wet argon, and dry oxygen at 450 °C for 30 min. The intensity of PL in a-Si₁₋xCx:H layers were enhanced by the factor from 2 to 12 after annealing in dependence on the annealing atmosphere. The strongest oxidation and strongest light emission were observed in carbon-rich series (x = 0.7) after annealing in oxidizing atmosphere. Structural properties of the films were characterized by infra-red absorption spectroscopy, ellipsometry and electron paramagnetic resonance. The effect of carbon enrichment of a-Si₁₋xCx:H films and annealing atmosphere on the evolution of photoluminescence and local interatomic bonding structure in annealed material were studied and analyzed. It has been found that main effects of thermal treatments is strong enhancement of photoluminescence accompanied by formation of Si:C–Hn and Si–OxCy bonding. The strongest oxidation effect as well as strongest hotoluminescence were observed in carbon-rich a-SiC:H films

Multiband light emission and nanoscale chemical analyses of carbonized fumed silica

Fumed silica with a specific area of 295 m(2)/g was carbonized by successive phenyltrimethoxysilane treatments followed by annealing in inert atmosphere up to 650 degrees C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated by steady state and time-resolved photoluminescence spectroscopies. The local chemistry was also studied by infrared transmission spectroscopy. Strong ultraviolet and visible photoluminescence was observed in the samples after the chemical treatments/modifications and thermal annealing. It has been shown that ultraviolet photoluminescence in chemically modified fumed silica is associated with phenyl groups, while near ultraviolet and visible emission in annealed samples originated from inorganic pyrolytic carbon precipitates dispersed in the silica host matrix. Two types of emission bands were identified as a function of the annealing temperature: one is in the near UV and the other is in the visible range. Based on the emission/excitation analysis of these two bands, as well as on correlations with the synthesis conditions, a structural-energy concept of light-emitting centers has been proposed. According to this model, the light-emitting centers are associated with carbon clusters that can be bonded or adsorbed on the silica surface. This has been validated by a detailed (S)TEM-electron energy-loss spectroscopy study, confirming the inhomogeneous distribution of nanoscale carbon precipitates at the surface of the silica nanoparticles. These carbon precipitates are mostly amorphous although they possess some degree of graphitization and local order. Finally, the fraction of sp(2) carbon in these nanoclusters has been estimated to be close to 80%. Published by AIP Publishing

Effect of chemical and radiofrequency plasma treatment on photoluminescence of SiOx films

Effect of hydrogen radiofrequency plasma and chemical treatment on photoluminescence (PL) spectra of SiOx layers containing Si nanoparticles are investigated. Considerable PL intensity growth in the samples containing Si nanocrystals (nc-Si-SiOx) after plasma treatment is observed. The process saturates for time of 15 minutes. Chemical treatment in ammonia and acetone vapour before thermal annealing of SiOx layers leads to the considerable changes in PL spectra effecting both on the band shape and on the intensity. The possibility of controlled changes in PL spectra in nc-Si-SiO₂ layers is shown

Novel hysteresis effect in ultrathin epitaxial Gd₂O₃ high-k dielectric

Charge trapping in ultrathin high-k Gd₂O₃ dielectric leading to appearance of hysteresis in C–V curves is studied by capacitance-voltage, conductance-frequency and current-voltage techniques at different temperatures. It was shown that the large leakage current at a negative gate voltage causes the reversible trapping of the positive charge in the dielectric layer, without electrical degradation of the dielectric and dielectricsemiconductor interface. The capture cross-sections of the hole traps are around 10⁻¹⁸ and 2 × 10⁻²⁰ cm² . The respective shift of the C–V curve correlates with a “plateau” at the capacitance corresponding to weak accumulation at the silicon interface

Electrical and light-emitting properties of silicon dioxide co-implanted by carbon and silicon ions

In this paper we explore the electrophysical and electroluminescence (EL) properties of thermally grown 350 nm thick SiO₂ layers co-implanted with Si⁺ and C⁺ ions. The implanting fluencies were chosen in such a way that the peak concentration of excess Si and C of 5-10 at.% were achieved. Effect of hydrogen plasma treatment on electroluminescent and durability of SiO₂ (Si,C) - Si-system is studied. Combined measurements of charge trapping and EL intensity as a function of the injected charge and current have been carried out with the aim of clarifying the mechanisms of electroluminescence. EL was demonstrated to have defect-related nature. Cross sections of both electron traps and hole traps were determined. EL quenching at a great levels of injected charge is associated with strong negative charge capture, following capture of positive charge leading to electrical breakdown of SiO₂ structures

Study of the Process e+e−→KL0KS0e^+e^- \to K^0_L K^0_S in the C.M.Energy Range 1.05-1.38 GeV with CMD-2

The process $e^+e^- \to K^0_L K^0_S$ has been studied with the CMD-2 detector using about 950 events detected in the center-of-mass energy range from 1.05 to 1.38 GeV. The cross section exceeds the expectation based on the contributions of the rho(770), omega(782) and phi(1020) mesons only.Comment: 12 pages, 3 figures, uses elsart.cls, submitted to Physics Letters