Explosive crystallization of a-Si films in both the solid and liquid phases

Abstract

In this letter, we show that explosive crystallization can occur sequentially along the same laser scan line either from the liquid phase or in the solid phase. Which phase dominates depends on the laser scan speed, the proximity of the a-Si melting isotherm, and the magnitude of the ’’thermal kick’’ provided by fluctuations in laser power or at localized regions of higher absorption.

Liquid-phase explosive crystallization of electron-beam-evaporated a-Si films induced by flash lamp annealing

“…The crystallization of precursor amorphous silicon (a-Si) films through non-thermal equilibrium rapid annealing has attracted considerable attentions since it is capable of forming device-grade polycrystalline Si (poly-Si) films on low-cost substrates with poor thermal tolerance [1][2][3][4][5][6][7][8][9][10]. Pulse duration for the crystallization is significantly important in order to fully heat and crystallize precursor a-Si films and to suppress thermal damage onto entire glass substrates, especially when thick ( 41 mm) a-Si films are used as precursor films with the aim of solar cell application.…”

Monitoring explosive crystallization phenomenon of amorphous silicon thin films during short pulse duration XeF excimer laser annealing using real-time optical diagnostic measurements

“…The melting point of a-Si is approximately 250°C lower than that of single-crystalline silicon (c-Si), because a-Si is in a higher free energy state than cSi and the transformation from the amorphous to the liquid state is a first-order phase transformation [5]. Previous studies have examined the significant role played by EC phenomenon of a-Si thin films in ELA [6,7].The phenomenon of EC is referred to as a process in which a crystallizing behavior advances rapidly or runs away from the optical, thermal or mechanical source, which was responsible for its initiation [8,9]. The optical diagnostic approaches are suitable for monitoring non-intrusively the melting and crystallization behavior of a-Si thin films because the reflectivity and transmissivity are good probing indicators of silicon films phase transformation.…”

Multicrystalline silicon films with large grains on glass: preparation and applications

“…In laser crystallization of amorphous silicon or other amorphous materials there may occur, as an intermediate effect, explosive crystallization [33,34]. This phenomenon is based on the facts that a-Si is metastable and has a latent heat of melting 20% lower than c-Si.…”