Crystallization Of Amorphous Si Research Articles

Influence of Annealing Time on Crystallization of Amorphous SI by SB

The Sb induced crystallization of physics vapor deposit amorphous silicon can be observed on sapphire substrates after annealing at 770 K. The influence of annealing time on crystallization of amorphous Si by Sb is investigated. We find the crystallization of amorphous silicon can occur at 770 K, even for a very short annealing time.

Structure of Magnetically Ordered Si:Mn

The structure studies of single crystalline silicon implanted at 340 K or 610 K with Mn+ ions (Si:Mn) and subsequently processed under atmospheric and enhanced hydrostatic pressure at up to 1270 K are reported. The defect structure was determined by an analysis of X-ray diffuse scattering around the 004 reciprocal lattice point and by electron microscopy. High resolution X-ray diffraction techniques based on the conventional source of radiation were used for this purpose. The crystal structure of Si:Mn and the Si1-xMnx precipitates in the implantation – disturbed layer were studied by synchrotron radiation diffraction in the grazing incidence geometry. Processing of Si:Mn results in crystallization of amorphous Si within the buried implantation – disturbed layer and in formation of Mn4Si7 precipitates. Structural changes are dependent both on temperature of the Si substrate at implantation and on processing parameters.

Structural relaxation of amorphous silicon carbide thin films in thermal annealing

Amorphous Si 0.4C 0.6 thin films were deposited by radio frequency magnetron sputtering onto non-heated single crystal Si substrates, followed by annealing at 800 °C or 1100 °C in the vacuum chamber. The chemical bond properties and atomic local ordering as a function of the annealing temperature were characterized by Auger electron spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Infrared absorption spectroscopy, X-ray diffraction, and Raman spectroscopy measurements. We have examined the evolution of microstructure in annealing-induced relaxation process, and investigated the initial stages of thermal crystallization of amorphous Si 0.4C 0.6. Meanwhile, the structure of excess C in the films also has been studied.

Uniform Poly-Si TFTs for AMOLEDs Using Field-Enhanced Rapid Thermal Annealing

Polycrystalline Si thin film transistors (TFTs) have been fabricated through solid phase crystallization using field-enhanced rapid thermal annealing (FE-RTA) system. The system consists of inline furnace modules for preheating and cooling of the glass substrates and a process module for rapid radiative heating combined with alternating magnetic field induction. The FE-RTA system enables crystallization of amorphous Si at high throughputs without any glass damages. While the typical grain structures of poly-Si by FE-RTA are similar to those of solid phase crystallization, the residual amorphous Si and intragranular defects are reduced.

Inkjet-Printed Metal-Colloid-Induced Crystallization of Amorphous Silicon

We demonstrate for the first time the crystallization of amorphous Si induced by Ni colloid printing using inkjet printing technology. An electrostatic inkjet nozzle having a needle inside a capillary was built in house, which was able to eject very fine droplets according to the applied electric voltage. Dots of Ni colloidal solution were formed in the prescribed position. Enhanced crystallization was observed at the Ni-colloid-printed sites. The probability of crystallization decreased with the Ni concentration in the solution. At and above 4 mass % Ni concentration, fully enhanced crystallization occurred. Furthermore, the orientation of crystallized Si grains was determined by electron-backscattering pattern (EBSP) analysis. The dependence of crystallization behavior on the Ni concentration was also investigated.

Electrical activity of intragrain defects in polycrystalline silicon layers obtained by aluminum-induced crystallization and epitaxy

Defect etching revealed a very large density (∼109cm−2) of intragrain defects in polycrystalline silicon (pc-Si) layers obtained through aluminum-induced crystallization of amorphous Si and epitaxy. Electron-beam-induced current measurements showed a strong recombination activity at these defects. Cathodoluminescence measurements showed the presence of two deep-level radiative transitions (0.85 and 0.93eV) with a relative intensity varying from grain to grain. These results indicate that the unexpected quasi-independence on the grain size of the open-circuit voltage of these pc-Si solar cells is due to the presence of numerous electrically active intragrain defects.

Analysis of excimer laser annealing of amorphous SiGe on La 2O 3//Si structures

The reduction of complementary metal oxide semiconductor dimensions through transistor scaling is in part limited by the SiO 2 dielectric layer thickness. Among the materials evaluated as alternative gate dielectrics one of the leading candidate is La 2O 3 due to its high permittivity and thermodynamic stability. However, during device processing, thermal annealing can promote deleterious interactions between the silicon substrate and the high- k dielectric degrading the desired oxide insulating properties. The possibility to grow poly-SiGe on top of La 2O 3//Si by laser assisted techniques therefore seems to be very attractive. Low thermal budget techniques such as pulsed laser deposition and crystallization can be a good choice to reduce possible interface modifications due to their localized and limited thermal effect. In this work the laser annealing by ArF excimer laser irradiation of amorphous SiGe grown on La 2O 3//Si has been analysed theoretically by a numerical model based on the heat conduction differential equation with the aim to control possible modifications at the La 2O 3//Si interface. Simulations have been carried out using different laser energy densities (0.26–0.58 J/cm 2), different La 2O 3 film thickness (5–20 nm) and a 50 nm, 30 nm thick amorphous SiGe layer. The temperature distributions have been studied in both the two films and substrate, the melting depth and interfaces temperature have been evaluated. The fluences ranges for which the interfaces start to melt have been calculated for the different configurations. Thermal profiles and interfaces melting point have shown to be sensitive to the thickness of the La 2O 3 film, the thicker the film the lower the temperature at Si interface. Good agreement between theoretical and preliminary experimental data has been found. According to our results the oxide degradation is not expected during the laser crystallization of amorphous Si 0.7Ge 0.3 for the examined ranges of film thickness and fluences.

Microstructural Characterization of Polycrystalline Si Films Grown by Vapor-Induced Crystallization of Amorphous Si Using Al ∕ Ni Chloride

A polycrystalline Si film with uniform and large grains can be grown by crystallizing with chloride vapor transport. At the initial stage of crystallization, the poly-Si grains had round-shaped cores with needles at the growth front. It showed that the needles were grown by the Ni-induced lateral crystallization process and the sidewall of the needles was enlarged by the Al-induced crystallization process. The needles were emerged coherently to an extent by the sidewall growth. As a result, a poly-Si film with grains larger than and fewer intragrain defects was obtained. The Ni concentration was constant through out the film thickness with a value of . The Al concentration at the surface was and was reduced below at 25 -nm depth. The thin film transistor utilizing the film showed an electron mobility of at a drain voltage of . But the threshold voltage was that is considered as relatively high due to Al doping.

Crystallization of Amorphous Silicon Thin Films Using Self-Limiting ALD of Nickel Oxide

The crystallization of amorphous Si (a-Si) thin films was performed using atomic layer deposition (ALD) of nickel oxide. Nickel oxide layers were deposited using nickel aminoalkoxide as a precursor in Ni and water as a precursor in oxygen. The presence of nickel oxide caused significant crystallization to occur in a-Si at 575 °C under a reducing atmosphere. Even one single ALD layer of nickel oxide was high enough to crystallize the a-Si thin films. Self-limiting layer controllability in ALD is useful in providing a catalytic layer for formation of polycrystalline Si thin films for application to large-scale flat panel displays. © 2007 The Electrochemical Society. [DOI: 10.1149/1.2666721] All rights reserved.

Methods of processing Si 3N 4/SiC nano-nano composites from polymer precursor

Three approaches have been attempted in this investigation to bring the grain size of silicon nitride and silicon carbide composites into the truly nanometric range, i.e., where the grain size of both silicon nitride and silicon carbide phases are within the 100 nm limit. The first approach was crystallization of amorphous Si–C–N bulk materials which were first synthesized by a processing route based on pyrolysis of polymer precursor in order to obtain the polycrystalline silicon nitride/silicon carbide composites with grain size of 30–50 nm with varied phase proportions. The second processing method was high pressure sintering. Oxide additives were incorporated into precursor pyrolysis-derived powders, and sintering was conducted at 1400–1600 °C under a pressure of 1–2 GPa. The crystallinity and grain size of the sintered product can be controlled by the sintering temperature. The third method was electric field assisted sintering. With decreased additive amounts, the grain size of the sintered materials can be controlled to grain diameter as small as 38 nm.

Transmission electron microscopy observations of Cu-induced directional crystallization of amorphous silicon

By annealing at 500°C for 1h with an electric field of 180V∕cm, a Cu-deposited a-Si/glass sample undergoes a partial crystallization of amorphous Si, whose microstructure is characterized by conventional and high-resolution transmission electron microscopy. The Si crystallites grow in the ⟨111⟩ and ⟨211⟩ directions with their {011} planes parallel to the amorphous Si film surface, assuming a needlelike shape. Copper silicides are not observed at the leading edges of the crystalline Si needles. The growth directions of ⟨111⟩ and the {011} surface plane orientations are accepted to arise from elastic anisotropy of c-Si and can be explained by considering the strain energy under the uniaxial stress state and the plane stress, equibiaxial strain state. Crystallization behavior of a-Si in the Ni∕a-Si layer is also briefly discussed.

Electric field-dependent Ni-mediated lateral crystallization of a-Si on SiO 2

Ni-mediated lateral crystallization of amorphous Si has been investigated under a wide range of electric fields (0–4000 V/cm). In the low field region (< 100 V/cm), lateral growth velocity at the cathode side was enhanced by applying an electric field. This achieved formation of poly-Si with a large area (∼ 50 μm) during low-temperature annealing (525 °C, 25 h). When the electric field exceeded 100 V/cm, the lateral growth velocity decreased with increasing the electric field strength. Under the extremely high electric field (> 2000 V/cm), directional growth aligned to the electric field was observed. These new findings will be a powerful tool to achieve new poly-Si with highly controlled structures.

Au-induced lateral crystallization of a-Si 1− xGe x ( x: 0–1) at low temperature

Au-induced lateral crystallization of amorphous Si 1− x Ge x ( x: 0–1) on SiO 2 at a low temperature (400 °C) has been investigated. Although the growth velocity decreased with increasing Ge fraction, growth velocity exceeding 20 μm/h was obtained for all Ge fractions. As a result, poly-Si 1− x Ge x with large areas (> 20 μm) was obtained at a low temperature (400 °C). This is a great advantage of Au-induced lateral crystallization compared with Ni. However, the concentrations in the surface regions (depth: 0–20 nm) of the lateral growth regions were high (10–30%), though those in the deeper regions (depth: 20–50 nm) were as small as 1–2%. Removing of the surface regions with the high Au concentrations and gettering of Au atoms in the deeper regions are necessary to apply the grown layers to the device fabrication.

Enlargement of grain in poly-Si by adding Au in Ni-mediated crystallization of amorphous Si using a SiNx cap layer

We have studied the effect of Au addition on Ni-mediated crystallization of amorphous silicon(a-Si) using a silicon–nitride (SiNx) cap layer. The Ni and Au particles were sputtered on the SiNx∕a-Si and then the samples were heated for crystallization at a temperature of 550 °C. We achieved disk-shaped grains and found that the grain size increased with increasing Au density when the Ni density was fixed at 2.45×1014∕cm2. We achieved a grain size of ∼45μm, however the a-Si could not be crystallized when Au density is higher than Ni density.

Directional growth in metal-induced lateral crystallization of amorphous Si under extremely high electric field

Abstract Metal-induced lateral crystallization of amorphous Si has been investigated under a wide range of electric fields (0–4000 V/cm). In the low field region ( 2000 V/cm), directional growth aligned to the electric field was observed. This new findings will be a powerful tool to achieve new poly Si with highly controlled structures.

Confinement effect of optical phonons in Si–Ge alloy nanocrystals

Si 1– x Ge x nanocrystals (nc-Si 1– x Ge x , x = ( 43 ± 1 ) % ) with sizes of 7 ∼ 16 nm were prepared using thermal crystallization of amorphous Si 1– x Ge x alloy. Nanocrystal shape, composition, size, and phonon property were obtained in terms of high-resolution transmission electron microscope observations and X-ray diffraction and Raman spectral analyses. It was revealed that each optical vibration mode (Ge–Ge, Ge–Si, or Si–Si mode) is of evident phonon confinement effect. Using dispersion relationship in whole Brillouin zone, we numerically simulate the Raman spectra (peak position and linewidth) of nc-Ge and nc-Si and some evident characters in phonon confinement effect are presented for comparison with those of nc-Si 1– x Ge x .

A Novel Vapor-Induced Crystallization of Amorphous Si Using the Transport of Al/Ni Chloride

Al/Ni chloride vapor has been employed for the first time to enhance the crystallization of amorphous Si (a-Si) films. a-Si films under the vapor at 480°C were completely crystallized in 5 h. At the initial stage of the vapor induced crystallization (VIC), the seed grains were nucleated evenly throughout the film and their grain size was uniform. The final grain size was larger than 10 μm, depending on the process conditions. The poly-Si films showed a very smooth surface with a roughness of 4.26 Å due to the double surface-oxide layer formed during the VIC process. © 2005 The Electrochemical Society. All rights reserved.

Directional Growth of Si Nanowires on Insulating Films by Electric-Field-Assisted Metal-Induced Lateral Crystallization

ABSTRACTMetal-induced lateral crystallization of amorphous Si has been investigated under a wide range of electric fields (0-4000 V/cm). In the low field region (&lt;100 V/cm), lateral growth velocity at the cathode side was enhanced by applying an electric field. This achieved formation of poly-Si with a large area (∼50 μm) during low-temperature annealing (525°C, 25 h). When the electric field exceeded 100 V/cm, the lateral growth velocity decreased with increasing the electric field strength. Under the extremely high electric field (&gt;2000 V/cm), directional growth aligned to the electric field was observed. This new findings will be a powerful tool to achieve new poly-Si with highly controlled structures.

400 °C Formation of poly-SiGe on SiO 2 by Au-induced lateral crystallization

Au-induced low-temperature (400 °C) crystallization of amorphous-Si 1− x Ge x ( x: 0–1) thin films on SiO 2 has been investigated. Although the growth velocity decreased with increasing Ge fraction, growth velocity exceeding 20 μ m/h was obtained in all Ge fractions. As a result, strain-free poly-Si 1− x Ge x with large areas (>20 μ m) were obtained at a low temperature (400 °C). These new polycrystalline SiGe films on insulator could be used for advanced system in display and three-dimensional ULSI.

Functionalization of Nanomaterials utilizing Pulse Thermal Processing

ABSTRACTPulse Thermal Processing (PTP) using a High Density Infrared (HDI) Plasma Arc Lamp has been investigated as an enabling manufacturing tool for processing nanomaterials and thin-films. HDI is a single source lamp that offers unique capabilities of processing broad areas with power densities approaching those of a laser. The extremely high radiant energies delivered by the plasma arc lamp provides heating rates approaching 600, 000°C/s through a single pulse on a millisecond time frame, thus allowing controlled diffusion on nano-meter scale. The ability to design the functionality of nanomaterials offers tremendous potential to exploit this technology for a wide range of applications based on nanotechnology. This present article discusses application of PTP using high-density plasma arc lamp to perform; a) phase transformation in FePt nanoparticle system for magnetic media applications, and b) crystallization of amorphous Si (a-Si) for photovoltaic and thin-film transistor (TFT) applications.