Variation of crystallization mechanisms in flash-lamp-irradiated amorphous silicon films

Ohdaira, Keisuke; Nishikawa, Takuya; Matsumura, Hideki

doi:10.1016/j.jcrysgro.2010.06.023

Cited by 21 publications

(16 citation statements)

References 13 publications

(23 reference statements)

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“…Beginning in the 1970s, several groups reported on self-propagating crystallization reactions in amorphous films grown by vapor deposition. Evaporated and sputter deposited films of Ge [41][42][43][44], CdTe, (In,Ga)Sb [45], Si [46], and silicon dioxide [47] undergo "explosive" crystallization (EC) reactions when stimulated at a point. Modern EC studies also identified various means for igniting amorphous films, including thermal [47], optical [43,46], and mechanical approaches [45,48].…”

Section: Research Leading To the Discovery Of Reactive Multilayersmentioning

confidence: 99%

“…Evaporated and sputter deposited films of Ge [41][42][43][44], CdTe, (In,Ga)Sb [45], Si [46], and silicon dioxide [47] undergo "explosive" crystallization (EC) reactions when stimulated at a point. Modern EC studies also identified various means for igniting amorphous films, including thermal [47], optical [43,46], and mechanical approaches [45,48]. It is important to note that "explosive" crystallization of amorphous films requires thick films, typically with thickness ranging from~2 to 100 μm [48][49][50][51].…”

Section: Research Leading To the Discovery Of Reactive Multilayersmentioning

confidence: 99%

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Reactive multilayers fabricated by vapor deposition: A critical review

2015

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a b s t r a c t a r t i c l e i n f o Available online xxxxReactive multilayer thin films are a class of energetic materials that continue to attract attention for use in joining applications and as igniters. Generally composed of two reactants, these heterogeneous solids can be stimulated by an external source to promptly release stored chemical energy in a sudden emission of light and heat. In this critical review article, results from recent investigations of these materials are discussed. Discussion begins with a brief description of the vapor deposition techniques that provide accurate control of layer thickness and film composition. More than 50 reactive film compositions have been reported to date, with most multilayers fabricated by magnetron sputter deposition or electron-beam evaporation. In subsequent sections, we review how multilayer ignition threshold, reaction rate, and total heat are tailored via thin film design. For example, planar multilayers with nanometer-scale periodicity exhibit rapid, self-sustained reactions with wavefront velocities up to 100 m/s. Numeric and analytical models have elucidated many of the fundamental processes that underlie propagating exothermic reactions while demonstrating how reaction rates vary with multilayer design. Recent, time-resolved diffraction and imaging studies have further revealed the phase transformations and the wavefront dynamics associated with propagating chemical reactions. Many reactive multilayers (e.g., Co/Al) form product phases that are consistent with published equilibrium phase diagrams, yet a few systems, such as Pt/Al, develop metastable products. The final section highlights current and emerging applications of reactive multilayers. Examples include reactive Ni(V)/Al and Pd/Al multilayers which have been developed for localized soldering of heat-sensitive components.

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Section: Research Leading To the Discovery Of Reactive Multilayersmentioning

confidence: 99%

Section: Research Leading To the Discovery Of Reactive Multilayersmentioning

confidence: 99%

Reactive multilayers fabricated by vapor deposition: A critical review

2015

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“…Of a variety of methods to form thin c-Si, the crystallization of precursor amorphous silicon (a-Si) films on lowcost substrates has been expected as a prospective candidate [1][2][3]. We have investigated the crystallization of a-Si films by flash lamp annealing (FLA), millisecond-order rapid annealing using a pulse light emitted from Xe lamps [4][5][6][7][8][9][10][11]. Because of its proper annealing duration, FLA can realize the sufficient heating of a micrometreorder thick a-Si film without serious thermal damage onto an entire glass substrate.…”

Section: Introductionmentioning

confidence: 99%

“…EC is a well-known crystallization mode generally seen in amorphous materials with higher enthalpy than crystalline material, showing lateral crystallization driven by the release of latent heat [6,8,9,11,13]. We sometimes observe an EC including solid-phase nucleation (SPN), which leaves behind 1 m spacing periodic microstructures [6,8,9], and sometimes see the other type of EC completely governed by liquid-phase epitaxy (LPE), which forms relatively large grains with a length of several tens of micrometres [9,11]. The evaluation of the velocity of lateral crystallization is thus quite important for the discussion of the fundamental physics of crystallization mechanisms.…”

Section: Introductionmentioning

confidence: 99%

A method to evaluate explosive crystallization velocity of amorphous silicon films during flash lamp annealing

Ohdaira

2014

Can. J. Phys.

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Flash lamp annealing (FLA) of micrometre-order thick amorphous silicon (a-Si) films can induce explosive crystallization (EC), high-speed lateral crystallization driven by the release of latent heat. We develop multipulse FLA system, which emits a quasi-millisecond pulse consisting of a number of subpulses. The emission frequency of the subpulses can be systematically controlled, and the emission of subpulses leads to the periodic modulation of the temperature of a Si film and the resulting formation of macroscopic stripe patterns. The relationship between a subpulse emission frequency and the width of the macroscopic stripe patterns yields EC velocity. Two kinds of EC modes can be observed, depending on the methods of precursor a-Si deposition and (or) a-Si film thickness.Résumé : Le recuit par lampe à décharge (FLA) de films de silicium amorphe (a-Si) peut causer une cristallisation spontanée (explosive) (EC) ou une cristallisation latérale induite, soutenue par le rejet de chaleur latente. Nous développons un système de recuit par lampe à décharge multi-pulse qui émet des impulsions presque milliseconde consistant en un nombre de sousimpulsions. La fréquence d'émission de ces sous-impulsions peut être contrôlée et l'émission de ces sous-impulsions mène à une modulation de la température du film de Si, d'où il résulte la formation d'un patron en bandes macroscopiques. La relation entre la fréquence d'émission des sous-impulsions et la largeur de ces bandes donne la vitesse de EC. Nous observons deux types de modes EC, dépendant de la méthode de déposition du précurseur Si et (ou) de l'épaisseur du film de a-Si. [Traduit par la Rédaction]

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“…Note that the EC observed for EB-evaporated films is different from previously reported SPN-dominant continuous EC, 20 a clear evidence of which is significantly different c-Si Raman peak widths, $9 cm À1 for poly-Si films crystallized through the SPN-dominant continuous EC. 20 We finally discuss the reason of the emergence of different EC modes depending on precursor a-Si films. One possible trigger of the variation of EC mechanisms is the film stress of precursor a-Si films.…”

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confidence: 96%

Lateral Crystallization Velocity in Explosive Crystallization of Amorphous Silicon Films Induced by Flash Lamp Annealing

Ohdaira

Tomura

Ishii

et al. 2011

Electrochem. Solid-State Lett.

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We propose a new method to estimate the explosive crystallization (EC) velocity (v EC ) of amorphous silicon (a-Si) films using multi-pulse flash lamp annealing (FLA). This system produces discrete pulses at frequencies of 1-10 kHz to form a quasi-millisecond pulse. The multi-pulses leave behind macroscopic stripe patterns on the surfaces of polycrystalline Si (poly-Si) films, the widths of which are indications of v EC . We find that catalytic chemical-vapor-deposited (Cat-CVD) and sputtered a-Si films show v EC of $4 m/s, whereas the use of electron-beam-evaporated a-Si results in much higher v EC of $14 m/s, indicating the emergence of different EC mechanisms.Rapid annealing using sub-second pulse light is of great importance as the methods of crystallizing precursor amorphous silicon (a-Si) films to form device-quality polycrystalline Si (poly-Si) films because of the availability of low-cost glass or plastic substrates. [1][2][3][4][5][6][7][8] This non-thermal equilibrium sub-second annealing sometimes induces explosive crystallization (EC), high-speed lateral crystallization driven by the release of latent heat. 9-15 It has been know that the EC of a-Si occurs in liquid-phase and/or in solid-phase, which results in different EC velocity (v EC ). 9-13 In-situ observation of EC, however, is not easy because of enormously high v EC on the order of m/s. Although v EC of a-Si films has been experimentally estimated by some of in-situ or ex-situ methods, 9,14 they require complicated experimental system or expensive equipments.We have so far found that flash lamp annealing (FLA), millisecond-order annealing using Xe lamps, can induce EC of a few m-thick a-Si films and the EC observed is based on solid-phase nucleation (SPN) and partial liquid-phase epitaxy (LPE), 16 unlike previously reported results that have shown the clear evidences of EC through simple LPE. 9 The v EC of Si films in the case of FLA, however, has not been evaluated, because of the difficulty of using an additional measurement system in a FLA system that has a character of large-area pulse emission. The purpose of this study is to utilize a quasi-millisecond multi-pulse FLA system, instead of conventional single millisecond-pulse FLA, in order to estimate the v EC of Si films from signatures left on poly-Si films formed due to multi-pulse emission which induces temperature modulation of Si during millisecond treatment. The determination of v EC can contributes to understand the mechanism of EC.We first formed 60-nm-thick Cr films on 20 Â 20 Â 0.7 mm 3 -sized quartz substrates by sputtering in order to suppress Si film peeling during FLA. 17 We then prepared 2-4 m-thick a-Si films formed by catalytic chemical vapor deposition (Cat-CVD), sputtering, and electron-beam (EB) evaporation on Cr-coated quartz glass substrates, the detailed deposition conditions of which are summarized in Table I. FLA system used in this study, produced by Design System Co., Ltd., can supply a quasi-millisecond pulse consisting of discrete sub-pulses emitted at variabl...

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Variation of crystallization mechanisms in flash-lamp-irradiated amorphous silicon films

Cited by 21 publications

References 13 publications

Reactive multilayers fabricated by vapor deposition: A critical review

Reactive multilayers fabricated by vapor deposition: A critical review

A method to evaluate explosive crystallization velocity of amorphous silicon films during flash lamp annealing

Lateral Crystallization Velocity in Explosive Crystallization of Amorphous Silicon Films Induced by Flash Lamp Annealing

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