Properties of thin LPCVD silicon oxynitride films

Thin, uniform silicon oxynitride films with films thicknesses of ≤ 10 nm were successfully deposited by low pressure chemical vapor deposition (LPCVD). The reactant gases were SiH₂Cl₂, N₂O, and NH₃. The compositional uniformity of these films as a function of depth was good. The structure of these oxynitride films was found to be dominated by the mixed matrix of Si, N, and 0, rather than a physical mixture of SiO₂ and Si₃N₄ clusters. N-H bonding was observed and the total amount of hydrogen in the as-deposited film was on the order of 5 x l0²⁰/cm³. No H-OH or Si-OH bonds were detected. Excellent dielectric breakdown distributions were found for oxynitride films with equivalent oxide film thicknesses as low as 7.5 nm. The conduction of Si-N-0 films depended on film composition. A small capacitor-voltage (C-V) window (< 0.1 V) was observed for the Si-N-O/Si structures. The midgap surface state density was on the order of 5 x 10¹⁰/cm² /eV. Either trapping of holes or the generation of positive states were found after high field stressing of the oxynitride films.     

Structural and electrical profiles for double damage layers in ion-implanted silicon

(111) Si specimens were implanted at room temperature with 5 × 1014 cm?2, 120 keVP+ ions, and annealed at 950°C. Transmission electron-microscope cross-section specimens revealed two discrete damage layers at depths of 95 and 190 nm. Electrical profiles showed decreases in carrier concentration and/or mobility at these two depths.     

Scalability and electrical properties of germanium oxynitride MOS dielectrics

In this letter, we present a fundamental study on the scalability and electrical properties of germanium oxynitride dielectrics for metal-oxide-semiconductor device applications. The nitrogen depth profile within the oxynitride dielectric layers was first monitored using angle-resolved x-ray photoemission spectroscopy and the dielectric permittivity variation was therefore identified. After thinning down the lower permittivity portion of these dielectrics, we successfully scaled down the capacitance-based equivalent SiO/sub 2/ thickness, in Ge MOS capacitors, to 1.9 nm without suffering from gate leakage. We have also investigated the effects of thermal annealing on various capacitor electrical properties. For instance, we measured a flat-band voltage shift of as much as -0.8 V from the ideal value on as-deposited capacitors and the recovery of the theoretical value, with acceptably small amount of oxide fixed charge, after subsequent thermal annealing. Lastly, we have benchmarked the performance of these oxynitride insulators with the advanced high-/spl kappa/ dielectrics on Ge and discussed the impacts on future scaling.     

Optical and electrical properties of thin wafers fabricated from nanocrystalline silicon powder

The infrared transmittance spectra and dark conductivity of wafers fabricated from nanocrystalline silicon powder (nc-Si) have been studied. The initial nc-Si powder is first synthesized by laser-induced silane dissociation, with the temperature of the surrounding buffer gas varied from 20 to 250°C, and then compacted at pressures from 10⁸ to 10⁹ Pa. It is found that compaction of the nc-Si powder results in formation of Si-H, Si-CH_x, and O_y-Si-H_x structures (x, y=1–3). The formed structures break down under annealing, with the Si-H and Si-CH_x complexes disintegrating at the lowest annealing temperature (t = 160°C). The dark conductivityof the nc-Si wafers is shown to increase along with the buffer gas temperature at which the starting powder was prepared. Two temperature regions are found in which the dark conductivity behaves in radically different ways. At wafer temperatures T ≥ 270 K, conductivity is mediated by free carriers, whereas, at lower temperatures, electron transport is governed by hopping conduction over localized states in the band gap.     

Structural and electrical properties of stable ni/cr thin films

The electrical and structural properties of nickel-chrome (NiCr) thin film resistors were studied for the effect of post-deposition annealing on stability. The temperature coefficient of resistance (TCR) of sheet resistivities in the range of 100 to 200 Ω/□ could be improved by both air and vacuum annealing to achieve 5 ± 5 ppm/°C over the temperature range of -180° C to +100° C. With stability tests, air annealing proved to be more favorable for stable TCR. Studies via SIMS and ESCA identified surface segregation of Cr whereas TEM micrographs revealed correlating structural transformation of the films upon annealing. An intentional impurity, Si, played an important role in achieving a low TCR.     

AZO透明导电薄膜的结构与光电性能

采用射频溅射工艺制备了Zn1-xAlxO透明导电薄膜。通过XRD、UV透射和电学性能测试等分析手段,研究了Al浓度对薄膜的组织结构和光电性能的影响规律。结果表明:薄膜具有c轴择优取向,随着Al浓度的增加,(002)衍射峰向高角度移动,峰强度逐渐减弱,x(Al)为15%掺杂极限浓度。x(Al)为2%时,薄膜电阻率是3.4×10–4Ω.cm。随着掺杂量x(Al)从0增加到20%,薄膜的禁带宽度从3.34 eV增加到4.0 eV。     

Structural,opto-thermal and electrical properties of ZnO:Mo sprayed thin films

Zinc oxide (ZnO) thin films doped with molybdenum (Mo) have been prepared by the spray pyrolysis technique. X-ray analysis shows that ZnO:Mo thin films crystallize in hexagonal structure with a preferred orientation of the crystallites along (002) direction. The surface topography of these films was performed by the atomic force microscopy. The dispersion of the refractive index was discussed in terms of the single oscillator model proposed by Wemple and DiDomenico. The single oscillator energy (E₀) as well as the dispersion energy (E_d) were therefore calculated. Finally, the electric conductivity was investigated depending on the effect of temperature. The activation energy (E_a) was found to range from 0.63 to 0.94 eV; the electrical behavior can be correlated with Mo-doping.     

Effect of si—h and n—h bonds on electrical properties of plasma deposited silicon nitride and oxynitride films

Strong correlations were observed between the improvement in the metal-insulator-semiconductor (MIS) (aluminum-nitride-semiconductor) electrical properties of plasma deposited silicon nitride and oxynitride films and their (Si—H/N—H) bonding ratios in the film bulk. Total hydrogen concentration and spin density of all deposited films decreased with post-deposition annealing. Films with more Si—H bonds and stable (Si—H/ N—H) ratios generally have lowerV _fb shift, less positive trap charge and higher breakdown dielectric strength. Silicon oxynitride films with refractive indices of 1.75-1.80, as-deposited and after annealing in forming gas (10% H₂ + 90% N₂) at various temperatures, were found to have stable (Si—H/N—H) bonding ratios, lower silicon dangling bond density, and better MIS electrical properties compared to other plasma deposited nitride and oxynitride films.     

Cathodoluminescence and photoluminescence of amorphous silicon oxynitride

The cathodoluminescence and photoluminescence of amorphous silicon oxynitride (a-SiO_xN_y) films with different compositions were measured for the first time in the near infrared to visible–ultraviolet range. The red band with energy at 1.8–1.9 eV, blue band with energy 2.7 eV, ultraviolet bands with energies 3.1, 3.4–3.6, 4.4–4.7, and 5.4 eV were observed in a-SiO_xN_y. The 1.8–1.9 eV band is attributed to the oxygen and nitrogen atoms with unpaired electrons and the 2.7 eV band is attributed to twofold coordinated silicon atoms with two electrons. The 5.4 eV shoulder is due to the peroxy radicals and other ultraviolet bands are supposed to be due to the Si–Si bonds.     

Structural, electrical and optical properties of ZnO thin films deposited by sol-gel method

Thin films of intrinsic and Al-doped ZnO were prepared by the sol-gel technique associated with spin coating onto glass substrates. Zinc acetate dehydrate, ethanol and monoethanolamine were used as a starting material, solvent and stabiliser, respectively. Structural, electrical and optical characterizations of the films have been carried out. All films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction 〈0 0 2〉. The four-points technique was used to characterize thin films electrically. All films exhibit a transmittance above 80-90% along the visible range up to 650 nm and a sharp absorption onset about 375 nm corresponding to the fundamental absorption edge 3.3 eV. Intense UV photoluminescence is observed for undoped and 1% Al-doped ZnO films.     

Structural and electrical properties of plasma-deposited silicon nitride from SiH4-N2 gas mixture

Plasma-deposited silicon nitride films were produced from SiH₄-N₂ gas mixture. Their composition, chemical bonds, and electrical properties were investigated by varying the deposition conditions. The silicon nitride films from SiH₄-N₂ gas mixture exhibit (i) less hydrogen, (ii) higher thermal endurance, (iii) higher density, and (iv) smaller etching rate than those of the films deposited from SiH₄, and NH₃ gas mixture. These results can be partly attributed to lower hydrogen concentration. As the Si/N ratio approaches the stoichiometric value, 0.75, the resistivity and the breakdown strength are increased. They are 10¹⁵Ωcm and 9MV/cm, respectively, at Si/N≃0.85. Interface state density between silicon and silicon nitride layers is as low as 1& #x223C; 5xl0¹¹cm⁻² eV⁻¹. On leave from The Northwest Telecommunication Engineering Institute, Xi’an, The People’s Republic of China.     

The electrical properties of phosphorus doped silicon layers obtained by ion implantation through a passivating oxide

The electrical properties of phosphorus doped silicon layers obtained by ion implantation through a passivating oxide are studied. The quality of the fabricated n⁺p diodes is investigated. The influence of the process parameters and of the crystal orientation on the sheet resistance of the n⁺ layers is studied. It is shown that sheet resistances higher than 1 kΩ/□ with a good linearity and a very low temperature coefficient can easily be obtained in a reproducible way.     

Metallurgical and electrical properties of chromium silicon interfaces

The effect of annealing treatment up to 500°C on CrSi contacts was studied from physico-chemical and electrical view points. The solid-solid reactions between a 1000 Å thick Cr layer and a 〈111〉N single crystal of silicon, were studied by the He⁺ ion backscattering method, X-ray diffraction and transmission electron microscopy. We first observed a growth in the Cr grains and then the nucleation and growth of the disilicide CrSi₂. For annealing temperatures greater than 415°C, the growth is linear in time with an activation energy of 1.5±0.1 eV and for lower temperatures it becomes superlinear. The growth mechanism is discussed in terms of growth limiting phenomena. The variations of the electrical parameters (ideality factor n and barrier height 0_Bn) as a function of 15 min anneals between 300 and 500°C were correlated to the physico chemical observations. We establish, firstly, an optimal temperature annealing range in order to obtain good Schottky CrSi diodes and, secondly, a low limit of Cr thickness which must be deposited to obtain acceptable Schottky CrSi₂  Si diodes after annealing.     

Classification of electrical properties of porous silicon

The classification of electrical properties of porous silicon is performed on the basis of differences in the structure of this material and in the processes of formation of the regions depleted of charge carriers. It is shown that porous silicon as a class can be subclassified into four groups, each of which has a specific set of characteristic features. For each group, the most probable properties of metal/(porous silicon) and (porous silicon)/(single-crystalline silicon) junctions are described. It is shown that the diversity of electrical properties of porous silicon and its contacts with metallic electrode and silicon substrate brings about the experimentally observed wide set of characteristics of multilayer structures with porous silicon layers.     

Electrical properties of thin Co2Si,CoSi, and CoSi2 layers grown on evaporated silicon

MeV⁴He⁺ backscattering spectrometry and CuK_α x-ray diffraction were used to measure the thicknesses and phases of Co-silicides grown from samples with a thin Co layer deposited on a thin Si layer evaporated on a SiO₂ substrate (SiO₂/Si^e/ Co). Uniform layers of Co₂Si, CoSi, and CoSi₂ were formed sequentially in a layer-by-layer manner. Electrical properties of these silicides were studied with four-point probe measurements. The results show that Co₂Si and CoSi₂ are p-type conductors and CoSi is n-type conductor with resistivity close to the reported values. Results from measurements that were performed on samples with two phases of silicide present (e.g. SiO₂/ Si^e/CoSi₂/CoSi) are explained very well by a simple model which assumes two layers of silicides connected electrically in parallel.     

Structural, electrical and optical properties of zinc oxide produced by oxidation of zinc thin films

We have investigated the effects of oxidation temperature on the physical properties of polycrystalline zinc oxide thin films. Zinc thin films are oxidized at different temperatures in air. We have found that increasing the oxidation temperature deteriorates the preferred c-axis orientation. Also, increasing the oxidation temperature enlarges the crystal size and increases the number of needle-shaped crystals on the surface of the ZnO samples. By increasing the oxidation temperature, more than zinc melting point, tensile stresses start to build up in the films. Also by increasing temperature, sheet resistance of the films decreases, while photoluminescence intensity ratio (green to orange) increases. Increasing the oxidation temperature reduces the transparency of the films, too. It is proposed that either an increase in the number of oxygen vacancies or a decrease in the volume of grain boundaries, is responsible for the observed behavior of the films at higher oxidation temperatures.     

Degradation and breakdown of thin silicon dioxide films underdynamic electrical stress

Thin oxide MOS capacitors have been subjected to dynamic voltage stresses of different characteristics (shape, amplitude and frequency) in order to analyze the transient response and the degradation of the oxide as a function of the stress parameters. The current transients observed in dynamic voltage stresses have been interpreted in terms of the charging/discharging of interface and bulk traps. As for the oxide degradation, the experimental data has been interpreted in terms of a phenomenological model previously developed for dc stresses. According to this model, the current evolution in voltage stresses is assumed to be related to the oxide wearout. The evolution of the current during bipolar voltage stresses shows the existence of two different regimes, the degradation being much faster at low frequencies than at high frequencies. In both regimes, the frequency dependence is not significant, and the change from one regime to the other takes place at a threshold frequency which depends on the oxide field. These trends are also observed in time-to-breakdown versus frequency data, thus suggesting a strong correlation between degradation and breakdown in dynamic stresses. The experimental results are discussed in terms of microscopic degradation models     

Ni-Al薄膜的制备和电性能研究

用双靶直流磁控共溅射制备了NixAl(1-x)(0.75相似文献   

Preparation and electrical properties of inas thin films

Thin films of InAs have been deposited on mica substrates through a vacuum evaporation technique by means of controlling the substrate and source temperatures. The films with large crystal grain were found to have the best electrical properties. The maximum electron mobility of 12, 400 cm²/V·sec at room temperature was obtained in an undoped film of 3 Μm thickness at a donor concentration of 3.5 × 10¹⁶ cm⁻³. The temperature dependence of both electron mobility and resistivity of these films was slightly lower than those reported for bulk crystal type InAs.     

Optical and electrical characterization of GaN layers grown on silicon and sapphire substrates

Characterization of the structural, optical and electrical properties of GaN layers grown by two epitaxial techniques (ECR-MBE and MOCVD) using different substrates (vicinal Si111 and sapphire) has been performed. The quality of the samples grown by MOCVD seems to be influenced by the nitrogen source used for the growth. Unintentionally doped MBE samples with n-type concentrations around 10¹⁸ cm⁻³ and Hall mobility of 15 cm² (V s)⁻¹ were studied. GaN films doped with Mg and grown using AlN buffer layers have also been analyzed to study the influence of the thickness of the buffer layer on the optical properties of the GaN epilayer. In the samples with low Mg doping, a thin AlN buffer layer improved the optical quality of the film. In general, all the MBE samples doped with Mg were highly resistive, probably due to a low activation or high ionization energy of the Mg acceptors. Technological issues related to the formation of ohmic contacts on GaN layers are also presented.