Lateral Grain Growth during the Laser Interference Crystallization of a-Si

Abstract

We used laser interference (LIC), a combination of pulsed laser crystallization and holography, to fabricate polycrystalline silicon lines in an amorphous silicon (a‐Si) film. Under appropriate conditions, the grains in the lines reach in‐plane dimensions appreciably larger than the thickness of the initial a‐Si film (up to 1.7 μm for a 300 nm a‐Si film). Atomic force and transmission electron microscopy indicate that these large grains result from the lateral solidification of the silicon lines melted by the laser pulse. The lateral growth is well reproduced by simulations of the LIC dynamics by means of a two‐dimensional melting and solidification model.

Epitaxial pulsed laser crystallization of amorphous germanium on GaAs

“…The width of 7 ns of the Nd:YAG pulses is shorter than those of over 20 ns of conventional excimer lasers. 13 The structural properties of the crystallized samples were investigated using cross-sectional TEM and Raman spectroscopy. 4,12 The laser beam profile was homogenized using a vacuum spatial filter, leading to a Gaussian-like intensity profile with a diameter 0 ϭ4 mm on the sample surface.…”

Silicon Oxide (SiOx, 0&ltx&lt2): a Challenging Material for Optoelectronics

“…This technique has been successfully utilized to change the structure of the various amorphous materials (carbon nitride (Zhang and Nakayama, 1997) or amorphous silicon (Aichmayr et al, 1998)). Thin films of various SiO x compositions have been irradiated with different fluxes of UV laser photons (λ=274 nm).…”

Laser interference structuring of a-Ge films on GaAs

“…6 The lateral temperature gradient induced by the selective illumination has also been applied to induce a lateral solidification of amorphous silicon films, which permits the control of grain size and orientation of the crystallized material. 3,4,7,8 In a previous work, 9 we have demonstrated that amorphous ͑a-͒ Ge films deposited on crystalline GaAs substrates can be epitaxially crystallized when irradiated by short laser pulses. The Ge/GaAs system is ideal for laser crystallization studies since the two materials are almost perfectly matched with respect to lattice constants and thermal expansion coefficients.…”

“…LIC allows for the fabrication of periodic structures in a ns time scale without the need for lithography. It has been employed to fabricate arrays of lines or of dots of polycrystalline silicon [2][3][4] and polycrystalline germanium 5 on glass substrates as well as for the structuring of crystalline GaAs/͑Al,Ga͒As multilayers. 6 The lateral temperature gradient induced by the selective illumination has also been applied to induce a lateral solidification of amorphous silicon films, which permits the control of grain size and orientation of the crystallized material.…”