Crystallization of Tin-Implanted Amorphous Silicon Thin Films

ABSTRACTThe crystallization of Sn-implanted amorphous silicon was studied as a function of tin implant dose and annealing conditions by transmission electron microscopy. The films were implanted at an energy of 110 keV with a dose in the range of 5 × 1014 to 5×1016 cm−2 and were annealed at a temperature in the range of 450°C to 550°C. An enhanced rate of crystallization in amorphous Si-Sn films compared to the non-implanted amorphous silicon films during thermal annealing was observed. The crystallization process of Si films implanted with tin at a dose of 2.5×1016 cm−2 or less is very similar to unimplanted silicon films except higher nucleation rates and shorter crystallization time were observed with increasing tin dose. Films implanted with tin at a dose of 2.5×1016 cm−2 or more display extremely rapid crystallization (3 hours at 450°C) and very fine grain structure (10 nm); no substantial grain growth has been observed during lurther annealing, but some single crystal-like areas were formed. In-situ annealing of silicon implanted to 5×1016 cm−2 showed that the crystallization process is enhanced by the formation of the liquid tin phase.

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Seed-Induced Crystallization of Amorphous Silicon for the Formation of Large-Grain Poly-Crystalline Silicon

ASME 2010 4th International Conference on Energy Sustainability, Volume 2 ◽

10.1115/es2010-90443 ◽

2010 ◽

Author(s):

Jason Trask ◽

Lin Cui ◽

Andrew J. Wagner ◽

K. Andre Mkhoyan ◽

Uwe Kortshagen

Keyword(s):

Amorphous Silicon ◽

Crystalline Silicon ◽

Amorphous Film ◽

Average Crystallite Size ◽

Dark Conductivity ◽

Film Deposition ◽

Grain Structure ◽

Crystallization Time ◽

Silicon Thin Films ◽

Initial Seed

A new method for reducing crystallization time of hydrogenated amorphous silicon thin films and more successfully controlling grain structure has been studied through seeding of the bulk matrix with nanocrystallites during film deposition. Films were deposited by a system in which crystallites and amorphous film were synthesized in separate RF-powered plasmas. Average crystallite size was confirmed to be 20 to 50 nm via TEM imaging. Several films with various initial crystallite population densities were produced, and their crystallization kinetics were studied via Raman spectroscopy throughout a staged annealing process. Seeded films consistently displayed a characteristic crystallization time less than the incubation time of unseeded control films. Furthermore, films with larger initial seed densities exhibited earlier crystallization onset. A separate study also was performed in which the dark conductivity was compared between films re-crystallized from various initial seed densities.

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Low-Temperature Crystallization of Amorphous Silicon Thin Films by Microwave Heating

MRS Proceedings ◽

10.1557/proc-471-173 ◽

1997 ◽

Vol 471 ◽

Author(s):

Jeong No Lee ◽

Yoon Chang Kim ◽

Yong Woo Choi ◽

Byung Tae Ahn

Keyword(s):

Amorphous Silicon ◽

Microwave Heating ◽

Solid Phase ◽

Silicon Film ◽

Structural Disorder ◽

Silicon Films ◽

Silicon Thin Films ◽

Conventional Furnace ◽

Si Films ◽

Temperature Crystallization

ABSTRACTMicrowave heating was utilized for the first time for solid phase crystallization of amorphous silicon films. Microwave heating lowered annealing temperature and reduced the annealing time for complete crystallization. For example, the amorphous silicon film deposited at 400 °C was fully crystallized in 3 h at 550 °C below which glass is available as a substrate. On microwave heating, the hydrogen in the amorphous films diffused out very quickly, but there was no change in structural disorder following hydrogen evolution. The lower temperature crystallization of a-Si films compared to conventional furnace annealing is due to the interaction between microwave and silicon atoms. The grain size of the crystallized silicon films was in the range of 0.55 to 0.78 μm, depending on the deposition temperature. These grain sizes are not so small comparing those of Si films by conventional furnace heating, while the crystallization processing time is much shorter.

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Crystallization of Amorphous Silicon Thin Films by Microwave Heating

MRS Proceedings ◽

10.1557/opl.2014.920 ◽

2014 ◽

Vol 1666 ◽

Cited By ~ 1

Author(s):

Tomohiko Nakamura ◽

Shinya Yoshidomi ◽

Masahiko Hasumi ◽

Toshiyuki Sameshima ◽

Tomohisa Mizuno

Keyword(s):

Thin Films ◽

Heat Treatment ◽

Amorphous Silicon ◽

Microwave Heating ◽

Volume Ratio ◽

Heated Sample ◽

Silicon Thin Films ◽

Scattering Spectra ◽

Raman Scattering Spectra ◽

Si Films

ABSTRACTWe report crystallization of amorphous silicon (a-Si) thin films and improvement of thin film transistors (TFTs) characteristics using 2.45 GHz microwave heating assisted with carbon powders. Undoped 50-nm-thick a-Si films were formed on quartz substrates and heated by microwave irradiation for 2, 3, and 4 min. Raman scattering spectra revealed that the crystalline volume ratio increased to 0.42 for the 4-min heated sample. The dark and photo electrical conductivities measured by Air mass 1.5 at 100 mW/cm2 were 2.6x10-6 and 5.2x10-6 S/cm in the case of 4-min microwave heating followed by 1.3x106-Pa-H2O vapor heat treatment at 260°C for 3 h. N channel polycrystalline silicon TFTs characteristics were improved by the combination of microwave heating with high-pressure H2O vapor heat treatment. The threshold voltage decreased from 5.3 to 4.2 V and the effective carrier mobility increased from 18 to 25 cm2/Vs.

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Role of grain boundaries in the epitaxial realignment of undoped and As-doped polycrystalline silicon films

Journal of Materials Research ◽

10.1557/jmr.1993.2608 ◽

1993 ◽

Vol 8 (10) ◽

pp. 2608-2612 ◽

Cited By ~ 1

Author(s):

C. Spinella ◽

F. Benyaïch ◽

A. Cacciato ◽

E. Rimini ◽

G. Fallico ◽

...

Keyword(s):

Heat Treatment ◽

Grain Structure ◽

Native Oxide ◽

Thermally Induced ◽

Si Substrates ◽

As Doping ◽

Fine Grain ◽

Si Films ◽

Polycrystalline Silicon Films ◽

Reduced Density

The early stages of the thermally induced epitaxial realignment of undoped and As-doped polycrystalline Si films deposited onto crystalline Si substrates were monitored by transmission electron microscopy. Under the effect of the heat treatment, the native oxide film at the poly-Si/c-Si interface begins to agglomerate into spherical beads. The grain boundary terminations at the interface are the preferred sites for the triggering of the realignment transformation which starts by the formation of epitaxial protuberances at these sites. This feature, in conjunction with the microstructure of the films during the first instants of the heat treatment, explains the occurrence of two different realignment modes. In undoped films the epitaxial protuberances, due to the fine grain structure, are closely distributed and grow together forming a rough interface moving toward the film's surface. For As-doped films, the larger grain size leaves a reduced density of realignment sites. Due to As doping some of these sites grow fast and form epitaxial columns that further grow laterally at the expense of the surrounding polycrystalline grains.

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Phonon Conduction Normal to Polysilicon Films on Diamond

ASME 2013 4th International Conference on Micro/Nanoscale Heat and Mass Transfer ◽

10.1115/mnhmt2013-22171 ◽

2013 ◽

Cited By ~ 4

Author(s):

Jungwan Cho ◽

Pane C. Chao ◽

Mehdi Asheghi ◽

Kenneth E. Goodson

Keyword(s):

Thermal Conductivity ◽

Transport Theory ◽

Phonon Scattering ◽

Phonon Transport ◽

Silicon Films ◽

Silicon Thin Films ◽

Transmission Electron ◽

Crystal Films ◽

Polysilicon Films ◽

Polycrystalline Silicon Films

Silicon films of thickness near and below one micrometer play a central role in many advanced technologies for computation and energy conversion. Numerous data on the thermal conductivity of silicon thin films are available in the literature, but mainly for the in-plane thermal conductivity of polycrystalline and single-crystal films. Here we use picosecond time-domain thermoreflectance (TDTR), transmission electron microscopy, and phonon transport theory to investigate heat conduction normal to polycrystalline silicon films on diamond substrates. The data agree with predictions that account for the coupled effects of phonon scattering on film boundaries and defects concentrated near grain boundaries. Using the data and the model, we estimate the polysilicon-diamond interface resistance to be 6.5–8 m2 K GW−1.

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Polysilicon Films Formed On Alumina By Aluminium Induced Crystallization Of Amorphous Silicon

MRS Proceedings ◽

10.1557/proc-0910-a21-01 ◽

2006 ◽

Vol 910 ◽

Cited By ~ 3

Author(s):

Etienne Pihan ◽

Abdelilah Slaoui ◽

Claude Maurice

Keyword(s):

Amorphous Silicon ◽

Grain Orientation ◽

Coincident Site Lattice ◽

Grain Structure ◽

Structural Quality ◽

Orientation Imaging ◽

Polysilicon Films ◽

Si Films ◽

Induced Crystallization

AbstractWe investigated the structural quality of polysilicon films fabricated by the aluminium induced crystallization (AIC) of amorphous silicon on alumina substrates. We analyzed the overall crystallographic quality of the poly-Si films in terms of grain size distribution and grain orientation versus crystallization temperature. For these studies, we used extensively the orientation imaging micrograph (OIM) technique, a very powerful tool that allows elucidating the inner-grain structure, the grain boundaries, the grain orientation. From our analysis, we may conclude that the polysilicon films formed by AIC on alumina substrates have the following features: (i) for all investigated temperatures, most of the silicon grains have a deviation angle from (100) crystallographic orientation between 5 and 25°; (ii) increasing the annealing temperature tends to decrease the (100) preferred orientation; (iii) the angular boundary distribution revealed that the main defects are those that have been observed inside isolated dentrites, namely low angle boundaries (<2°) and coincident site lattice boundaries such as Σ3, Σ9 and Σ27.

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Low Temperature Crystallization of Amorphous Silicon Films Using an Excimer Laser

MRS Proceedings ◽

10.1557/proc-149-345 ◽

1989 ◽

Vol 149 ◽

Cited By ~ 13

Author(s):

S. E. Ready ◽

J. B. Boyce ◽

R. Z. Bachrach ◽

R. I. Johnson ◽

K. Winer ◽

...

Keyword(s):

Amorphous Silicon ◽

Excimer Laser ◽

Laser Energy ◽

Amorphous Material ◽

Surface Region ◽

Silicon Films ◽

Starting Material ◽

Near Surface ◽

Silicon Thin Films ◽

Crystallite Sizes

ABSTRACTIn an effort to enhance the electrical properties of silicon thin films, we have performed recrystallization experiments on a variety of amorphous silicon films using an excimer laser. The intense, pulsed UV produced by the laser (308nm, using XeCl gas) is highly absorbed by the amorphous material and thus provides intense localized heating in the near surface region. Two types of starting films were studied: plasma CVD a-Si:H and LPCVD a-Si. The subsequent modification produces crystallites whose structure and electrical characteristics vary due to starting material and laser scan parameters. The treated films have been characterized using Raman, x-ray diffraction, TEM, SIMS and transport measurements. The results indicate that crystallites nucleate in the surface region. The degree of crystallization near the surface increases dramatically as a function of deposited laser energy density and less so as a function of laser shot density. The hall mobility of the highly crystallized samples exhibit an increase of 2 orders of magnitude over the amorphous starting material. In the PECVD material, the rapid diffusion of hydrogen causes voids to be formed at intermediate laser energy densities and removal of film at higher energy densities. The LPCVD material withstands the high laser energies to produce well crystallized films with crystallite sizes greater then 1000Å.

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Characterization of Structure and Mechanical Properties of MoSi2-SiC Nanolayer Composites

MRS Proceedings ◽

10.1557/proc-322-27 ◽

1993 ◽

Vol 322 ◽

Cited By ~ 3

Author(s):

H. Kung ◽

T. R. Jervis ◽

J-P. Hirvonen ◽

M. Nastasi ◽

T. E. Mitchell

Keyword(s):

Mechanical Properties ◽

Structural Changes ◽

Crystallization Process ◽

Mechanical Response ◽

Cross Sectional ◽

Annealing Conditions ◽

Transmission Electron ◽

Layer Structures ◽

Amorphous Structures

AbstractA systematic study of the structure-mechanical properties relationship is reported for MoSi2-SiC nanolayer composites. Alternating layers of MoSi2 and SiC were synthesized by DCmagnetron and if-diode sputtering, respectively. Cross-sectional transmission electron microscopy was used to examine three distinct reactions in the specimens when exposed to different annealing conditions: crystallization and phase transformation of MoSi2, crystallization of SiC, and spheroidization of the layer structures. Nanoindentation was employed to characterize the mechanical response as a function of the structural changes. As-sputtered material exhibits amorphous structures in both types of layers and has a hardness of 11GPa and a modulus of 217GPa. Subsequent heat treatment induces crystallization of MoSi2 to form the C40 structure at 500°C and SiC to form the a structure at 700°C. The crystallization process is directly responsible for the hardness and modulus increase in the multilayers. A hardness of 24GPa and a modulus of 340GPa can be achieved through crystallizing both MoSi2 and SiC layers. Annealing at 900°C for 2h causes the transformation of MoSi2 into the Cllb structure, as well as spheroidization of the layering to form a nanocrystalline equiaxed microstructure. A slight degradation in hardness but not in modulus is observed accompanying the layer break-down.

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A Study on the Metal Induced Lateral Crystallization Behavior of Amorphous Silicon Thin Films

MRS Proceedings ◽

10.1557/proc-441-101 ◽

1996 ◽

Vol 441 ◽

Cited By ~ 1

Author(s):

Byung-Il Lee ◽

Kwang-Ho Kim ◽

Won-Cheol Jeong ◽

Pyung-Su Ahn ◽

Jin-Wook Shin ◽

...

Keyword(s):

Thin Films ◽

Amorphous Silicon ◽

Crystallization Behavior ◽

Crystallization Rate ◽

External Stress ◽

Tem Analysis ◽

Silicon Thin Films ◽

Amorphous Si ◽

Lateral Crystallization ◽

Si Films

AbstractBasic mechanisms for both Ni- and Pd-metal induced lateral crystallization (MILC) are investigated. For both cases, tiny silicides were formed under the metal deposited area, and propagated toward amorphous Si films leaving crystallized Si behind at temperatures as low as 500 °C. Ni-MILC was influenced by Pd such that the lateral crystallization rate was enhanced, and the temperature for the lateral crystallization was lowered to 450 °C. Through TEM analysis and external stress experiments, it was found that the enhancement of the lateral crystallization rate was closely related to the compressive stress generated by the formation of nearby Pd2Si.

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