Solid-phase crystallization of Si1−xGex alloy layers

Abstract

Solid-phase crystallization of Si1−xGex (x=0–1.0) alloy layers deposited on a Si (100) substrate was investigated by ellipsometric spectroscopy. From a dispersion analysis of dielectric spectra, we deduced a crystallinity corresponding to the degree of average lattice alignment of the composed polycrystalline Si1−xGex layers and investigated the dynamical change in crystallinity during crystallization. We found that the crystallinity and crystallization temperature (TC) rapidly decreased with increasing Ge concentration (x). When x was small (=0–0.3), the highest crystallinity was ∼0.8 of that for single crystals while the lowest one was considerably below 0.6 when x>0.8. Moreover, the crystallinity decreased with increasing temperature above TC. We investigated the nucleation rate during crystallization and found that the decrease in crystallinity at both large Ge concentration and high temperature can be explained by a trade-off between the nucleation and crystallization rates; nucleation was dominant under these conditions. An overview of the crystallinity of solid-phase crystallized Si1−xGex alloy layers is provided.

Low-temperature solid-phase crystallization of amorphous SiGe films on glass by imprint technique

“…However, the acceleration ratio of the Ni-imprint samples decreased with increasing Ge fraction. This Ge dependence can be explained on the basis of the Ge dependence of the activation energy for spontaneous nucleation, i.e., the activation energy for spontaneous nucleation is significantly decreased with increasing Ge fraction [2], and thus, the acceleration effect by Ni-imprint is weakened with increasing Ge fraction. Further study is needed to clarify this mechanism.…”

“…Melt-grown processes such as laser annealing realize the growth of poly-SiGe with large grains ($5 lm); however, Ge atoms are not distributed uniformly in films, and surface ripples with $15 nm height were observed [1]. The solid-phase crystallization (SPC) of a-SiGe realizes both the uniform distribution of Ge atoms and the flat surface; however, high-temperature annealing (>550°C) is required [2][3][4].…”

Effect of Sn on crystallinity and electronic property of low temperature grown polycrystalline-Si1−−Ge Sn layers on SiO2

“…The energy band gap of poly-Si 1Àx Ge x with an Si content as high as 20% is as large as 1 eV which is comparable to bulk Si, hence sufficient low off-leakage current can be expected in poly-Si 1Àx Ge x metaloxide-semiconductor field effect transistors. The formation of poly-Si 1Àx Ge x layer by using solid phase crystallization (SPC) from amorphous phase has been reported [2][3][4]. However, the crystallization temperature of poly-Si 1Àx Ge x is generally as high as 550-700°C [2], and such a high crystallization temperature is not suitable for the fabrication process of 3D ULSI devices.…”

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

“…To achieve this, various recrystallization processes of a-Si on SiO 2 have been widely investigated. However, only poly Si with small grains (o0.1 mm) was obtained by solid-phase crystallization (SPC), even after a very long annealing time ($20 h) [1,2]. Melt-grown processes such as laser annealing realized poly Si with large grains ($5 mm); however, surface ripples with $15 nm height were observed [3].…”