Pulsed Laser Annealing of Thin Silicon Films

Abstract

Using Monte Carlo simulations and self-consistent field (SCF) theory we study the surface and interface properties of a coarse grained off-lattice model. In the simulations we employ the grand canonical ensemble together with a reweighting scheme in order to measure surface and interface free energies and discuss various methods for accurately locating the wetting transition. In the SCF theory, we use a partial enumeration scheme to incorporate singlechain properties on all length scales and use a weighted density functional for the excess free energy. The results of various forms of the density functional are compared quantitatively to the simulation results. For the theory to be accurate, it is important to decompose the free energy functional into a repulsive and an attractive part, with different approximations for the two parts.Measuring the effective interface potential for our coarse grained model we explore routes for controlling the equilibrium wetting properties. (i) Coating of the substrate by an oxide layer gives rise to a subtle interplay between shortrange and long-range forces,which may stabilize a film of mesoscopic thickness or result in the formation of nano-droplets. (ii) Coating the substrate with a polymer brush, we observe second-order wetting transitions at intermediate grafting densities, while the wetting transition is of first order at low and high grafting densities. In the latter limit, polymers of the same chemical structure as the brush do not wet the surface (autophobicity). (iii) Surface pattern (stripes) might give rise to unusual adsorption properties, which are related to morphological transitions. We relate our findings to experiments and discuss perspectives and limitations of the computational methods.

Physical mechanism for photon emissions from group-IV-semiconductor quantum-dots in quartz-glass and thermal-oxide layers

“…In this work, we experimentally studied the influence of the impurity density and dangling-bond density on the PL properties of IV-QDs (Si-and SiC-QDs) 23) fabricated by hotion implantations into OX or quartz-glass (QZ) with very low impurities. 24,25) We evaluated the influence of the impurity density on the PL properties of IV-QDs in QZ owing to an acceptor/donor ion implantation into QZ. The I PL of IV-QDs in QZ was much smaller than that of IV-QDs in OX, but SiC-QDs in acceptor or donor doped QZ showed the I PL improvement owing to multiple-level emissions.…”

A reliable approach to a rapid calculation of the grain size of polycrystalline thin films after excimer laser crystallization

“…[7][8][9][10][11][12][13][14][15][16][17] Numerous researches have been done for fabricating large-grained poly-Si thin films because the performance of TFTs is significantly affected by the size of the poly-Si thin films after ELC. [18][19][20][21][22][23] Until now, however, the grain size of the poly-Si thin films after ELC has usually been determined with a manual calculation. This approach included certain disadvantages such as human error and was time-consuming and exhausting.…”

Experimental Study on Surface-Orientation/Strain Dependence of Phonon Confinement Effects and Band Structure Modulation in Two-Dimensional Si Layers

“…On the other hand, the QCEs are reported to modulate the 2D Si band structures, and thus, to change the Si crystals to a direct band-gap material from an indirect band-gap 3D Si. 3,7,18,19) In addition, even in the Si material, PL has been observed in low-dimensional porous-Si (p-Si), 20) polycrystalline Si, 21) and even thin-film Si, 3,19,22,23) which is caused by strong QCEs. In particular, it is also reported that the T S dependence of peak photon energy is caused by the direct optical transmission in the direct band-gap thin-film Si material that is changed from the indirect band-gap bulk Si material.…”