Monosilane Gas Research Articles

Novel design of uniform Si@graphite@C composite as high-performance Li-ion battery anodes

We design a novel [email protected]@C composite via the pretreatment of graphite, subsequent deposition of Si nanoparticles via chemical vapor deposition, and finally the coating of carbon layer. The enlarged macropores of graphite can accommodate more loading of Si nanoparticles and the use of monosilane gas as source can bring the uniform deposition of Si nanoparticles in the whole graphite microparticles. The [email protected]@C composite has good electrical conductivity and can well accommodate the volume change during the charge/discharge process, thus result in a good electrochemical performance. The relationship between pore size distribution, Si particles distribution and electrode performance is also investigated.

Осаждение аморфных и микрокристаллических пленок кремния газоструйным плазмохимическим методом

Using gas-jet plasma-chemical method with gas activation by an electron beam, uniform thin films of amorphous and microcrystalline silicon in the forevacuum pressure range were obtained. Effects of argon carrier gas flow rate, monosilane gas concentration, background pressure in the reaction chamber, the substrate material, and the magnitude of the activating electron beam current on the deposition rate, photosensitivity, and crystallinity of silicon layers were studied. Deposition rate above 1 nm/s was achieved for films of amorphous silicon, and for layers with crystallinity about 60% the deposition rate was exceeded 0.6 nm/s. It is established that the substrate material does not affect the structure of the deposited silicon layers and their deposition rate.

Synthesis of nanocrystalline silicon thin films using the increase of the deposition pressure in the hot-wire chemical vapour deposition technique

Nanostructured thin silicon-based films have been deposited using the hot-wire chemical vapour deposition (HWCVD) technique at the University of the Western Cape. A variety of techniques including optical and infrared spectroscopy, Raman scattering spectroscopy, X-rays diffraction (XRD) and transmission electron microscopy (TEM) have been used for characterisation of the films. The electrical measurements show that the films have good values of photoresponse, and the photocurrent remains stable after several hours of light soaking. This contribution will discuss the characteristics of the hydrogenated nanocrystalline silicon thin films deposited using increased process chamber pressure at a fixed hydrogen dilution ratio in monosilane gas.

Development of New Hydrogenated Amorphous Silicon Thin Films with Quantum Wires

A new type of hydrogenated amorphous silicon (a-Si:H) thin film with nanowires was formed by applying a bias electric field along the growth surface of an a-Si:H thin film during a glow discharge in monosilane gas. Analyses of structural, electrical and optical properties revealed that nanoparticles with a radius of approximately 20 nm were formed and grew into nanowires with a length of 1 µm on the a-Si:H thin film surface as the bias electric field increased. In comparison with the carrier mobility of a conventional a-Si:H thin film, the carrier mobility of the nanowire estimated from the anisotropic electric conductivity was inferred to increase by up to three orders of magnitude or more. The dependence of the electric field on the optical band gap implies that quantum wires exist in the nanowire. These results suggest that quantum wires were formed in nanowires because of the effect of the bias electric field on the surface reaction of radicals along the growth surface during glow discharge.

High-rate deposition of hydrogenated amorphous silicon films using inductively coupled silane plasma

Inductively coupled plasma (ICP) generated at 13.56 MHz has been employed for high-rate deposition of device-quality hydrogenated amorphous silicon (a-Si:H). It has been shown that an increase in the flow rate of a monosilane gas enhances the generation rate of deposition precursors, while the ion flux decreases and becomes saturated. The defect density reaches the minimum at a deposition rate of 2.3 nm/s. It has also been demonstrated that even at deposition rates around 4 nm/s, a-Si:H deposited at 150°C exhibits a subgap defect density lower than ∼6×10 16 cm −3 after 12 h AM1 (100 mW/cm 2) light soaking.

Control of self-assembling formation of nanometer silicon dots by low pressure chemical vapor deposition

The formation of nanometer-scale silicon dots on ultrathin SiO2 layers has been studied by controlling the early stages of low-pressure chemical vapor deposition (LPCVD) of a monosilane gas. It has been suggested that the thermal dissociation of surface Si–O bonds plays a role in creation of nucleation sites on as-grown SiO2 and that surface Si–OH bonds formed by a dilute HF treatment or pure water immersion act as nucleation sites during LPCVD. By spatially controlling OH-termination on the SiO2 surface before LPCVD, the selective growth of Si dots has been demonstrated.

Initial Growth of Microcrystalline Silicon on Atomically Flat Hetero-Substrate

ABSTRACTInitial growth of microcrystalline silicon μ-Si:H) deposited on an atomically flat GaAs (001) wafer using a RF glow-discharge decomposition of hydrogen diluted monosilane gas mixture has been studied by means of atomic force microscope (AFM), Auger electron spectroscopy (AES), and cross-sectional transmitssion electron microscopy (XTEM).It is shown that the initial growth of μc-Si:H deposited at a substrate temperature of 50∼250°C consists of four successive stages, i.e., (1) a layer-by-layer growth of a-Si:H up to d ∼5 Å, (2) island formation of a-Si:H, (3) the coalescence of the islands and the nucleation of microcrystallite at d∼ 10–40 Å depending on the growth temperature, and (4) a rapid roughening with microcrystalline growth.

Low Temperature Deposition of Gate Silicon Dioxide Film for Thin Film Transistors by Photoassisted Remote Plasma Chemical Vapor Deposition Method

High quality silicon dioxide films with low leakage current and low surface charge density were deposited by a photoassisted remote plasma chemical vapor deposition (PAP-CVD) method at 330° C. Oxygen gas excited in a plasma which is kept apart from the wafer, was transported to the wafer and reacted with monosilane gas to generate intermediates. The adsorbed intermediates on the wafer were photoexcited to produce silicon dioxide films. Since the energy and the flux of incident ions to the wafer are suppressed to be as low as 1.4 eV and 1.3×1013 cm-2 s-1, respectively, high-quality films with low leakage current and low surface charge density were successfully deposited at low temperature. The silicon dioxide film fabricated by the PAP-CVD method is suitable for use as the gate insulator of a thin film transistor (TFT).

Quantitative Analysis of Trace Water in Monosilane Gas Using Atmospheric-Pressure Ionization Mass Spectrometer with Bicompartment Ion Source

Quantitative analysis of trace amount of water at the ppb level or less in monosilane gas was conducted using an atmospheric-pressure ionization mass spectrometer with a bicompartment ion source which prevents Si compound deposition in the ion source. Water ion which is not detected in the usual form of H2O+ due to the lower ionization potential of SiH3+ than that of H2O+, was detected as cluster ions (SiH3OH2)+, (SiH3OH2H2O)+, (Si2H5OH2)+ and (Si2H5OH2H2O)+. These ions were identified by the collision-induced dissociation method. The intensity of each of these ions changed with monosilane concentration. An independent calibration curve of monosilane concentration was obtained from the total intensity of these ions. In this raw monosilane gas, about 20 ppb of water was detected. This was decreased to 2.5 ppb upon using an adsorption-type purifier. The detection limit (S/N) was estimated to be 5 ppt.

Electron swarm parameters in SiH/sub 4/-rare gas mixtures and collision cross sections for monosilane molecules

Previously measured drift velocities and longitudinal diffusion coefficients in SiH/sub 4/-Ar mixtures were reanalyzed, and the new vibrational excitation cross sections for monosilane molecules were obtained. Not only were the new cross sections consistent with swarm parameters, but also the ratio of their magnitudes at the resonance peak agreed with earlier measurements of the electron beam experiment. Having known the vibrational excitation cross sections, the analysis of the primary ionization coefficient measured in SiH/sub 4/-Kr mixtures led to a consistent inelastic cross section, which possibly corresponds to the total section for neutral dissociations for the molecule. It was confirmed that the derived set of the cross sections also gave good agreement with the electron swarm parameters measured in pure monosilane gas.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Electron collision cross sections for the monosilane molecule

In monosilane-argon mixtures the measured electron swarm parameters, the drift velocity and the longitudinal diffusion coefficient showed distinctive features: humps in the drift velocity and dents in the ratio of the longitudinal diffusion coefficient to the electron mobility. These swarm parameters were analysed using a Boltzmann analysis and these features in the swarm parameters were conveniently used to derive a reasonable energy dependence of the vibrational excitation cross sections of a monosilane molecule. The derived cross sections were also confirmed to be consistent with published electron swarm parameters in pure monosilane gas.

Hochreines Monosilan für die Elektronikindustrie – Synthese, Reinigung und Charakterisierung

AbstractHigh‐purity monosilane for the electronics industry – Synthesis, purification, characterization. Monosilane is used in the electronics industry in the production of integrated circuits and in the manufacture of amorphous silicon devices such as solar cells, photocopier drums, and flat TV screens. The first German production unit for high purity monosilane gas which came on stream in 1987 is presented. The gas produced in a molten salt process is purified to highest quality and analyzed.

Optical and electrical properties of amorphous silicon films prepared by photochemical vapor deposition

Amorphous silicon films have been prepared through mercury-photosensitized decomposition of monosilane gas at low temperatures. The films show optical and electrical properties comparable with those of the best films prepared by plasma chemical vapor deposition. The feasibility of amorphous solar cells with short-circuit current densities of more than 10 mA/cm2 has been demonstrated by fabrication of a Schottky barrier structure.

Totally Depleted Surface Barrier Detectors Made of Ultra-High Purity P-Type Silicon Crystals

Thick Surface Barrier Detectors were developed using new ultra-high-resisitivity (~100KΩ·cm) p-type Si crystals, which were crystalized from monosilane gas, after being purified through molecular sieves. The detectors have vacuum evaporated electrodes of Al on a surface and of Au on another, and their thickness are 12-13 mm. It was confirmed through this work, surface treatment to generate an accumulation layer to the Au side improved the charge collection. The fabrication procedures and performances of the detectors are discussed.

Fabrication of Ultra High Purity Silicon Single Crystals

ABSTRACTHigh resistivity silicon single crystals for radiation detectors were grown by the floating-zone (FZ) method with and without one-pass zone refining of ultra pure starting material obtained by the decomposition of monosilane gas. In this method, boron is removed from monosilane during gas generation. The main residual impurity is phosphorus from phosphine which is removed with zeolite A after distillation of monosilane. Photoluminescence analysis and an improved 4-point probe resistivity measuring method were used to evaluate the material.

Thick Surface Barrier Detectors Made of Ultra-High Purity P-Type Si Single Crystal

ABSTRACTThe detector material used in this experimments is Ultra-High Purity p-type Si crystal. The material was single-crystalized through floating zone process from poly-crystal grown by thermal decomposition of highly refined mono-silane gas which had been purified by molecular sieves of specially prepared Zeolite powder.The resisitivity at room temperature is normally above 30 kΩ.cm, and the value of the highest grade ones exceeds 100kΩ.cm which corresponds to the Boron concentration of 1.5×l011 B/cm3.The potentiality of this material for detector use was investigated through Surface Barrier Detector fabrication. Detectors of above 4 mm thick and of excellent characteristics both at room temperature and at liq. N2 temperature could readily be fabricated. Owing to tie extremely high resisitivity, detectors can be made either partially depleted or totally depleted simply by properly selecting the wafer resisitivity and the thickness.In detector fabrication, the proper surface chemical treatment is very important, and seriously affects the leakage current and breakdown characteristics.Ultra-High Purity Si is promising as new detector material and has good potentiality to replace Si(Li) as followings:1) simple and easy detector fabrication,2) potentiality of thick detector fabrication (∼1cm),3) no precipitation problem of Li ions, and4) feasibility of thick ⊿E detector with thin entrance window on both faces.

Ultra-High Purification of Monosilane Gas for Semi-conductor Silicon

Ultra-High Purification of Monosilane Gas for Semi-conductor Silicon