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F3.24.1

PATTERNED STRUCTURES OF SILICON NANOCRYSTALS PREPARED BY PULSED LASER INTERFERENCE CRYSTALLIZATION OF ULTRA-THIN A-SI:H SINGLE-LAYER Xiaowei Wang, Feng Qiao, Leyi Zhu, Wei Li, Jian Li, Xinfan Huang, Kunji Chen National Laboratory of Solid State Microstructures and Department of Physics Nanjing University, Nanjing 210093, China ABSTRACT We employ the method of phase-modulated KrF excimer pulsed laser interference crystallization to fabricate nanometer-sized crystalline silicon (nc-Si) with the two-dimensional (2D) patterned distribution within the ultra-thin a-Si:H single-layer. The local crystallization occurs after interference laser irradiation under proper energy density. The results of atomic force microscopy, Raman scattering spectroscopy, cross-section transmission electron microscopy and scanning electron microscopy demonstrate that Si nano-crystallites are formed within the initial a-Si:H single-layer, selectively located in the discal regions with the diameter of 350 nm and patterned with the same 2D periodicity of 2.0 µm as the phase-shifting grating. The results show that the present method can be used to fabricate patterned nc-Si films for device applications. INTRODUCTION Nanometer-sized crystalline silicon (nc-Si) has long been the subject of great interest due to its potential application in the future optoelectronics and nano-electronics [1-7]. One important need for the commercial application of silicon–based device is to find a manufacturing technique that can control the sizes and the densities of nanocrystals as well as their positions. Moreover, such technique must be compatible with standard Si microelectronics process. For the purpose of device application, in many cases, patterned nc-Si structures are necessary [8]. However, for the patterned generation, the standard technique of optical lithography is limited by its resolution capability and its indirect technique process. Although the focused electron beam or ion beam technique overcomes the shortcomings of optical lithography, it requires expensive equipment and its yield is low for large-scale production due to its serial scanning process. Therefore, it is also limited for a wide use. In the last decade, the method of pulsed laser interference crystallization with two/multi-beam-interference system has been reported for preparing microcrystalline-silicon (µc–Si) films. By this method, a one/two dimensional interference pattern is achieved [9-11]. In our previous work, by the method of phase-modulated KrF excimer pulsed laser interference crystallization (LIC), we have successfully fabricated one-dimensional (1D) self-organized Si dots in a-Si:H films which is 50 nm thick [12]. Further, by LIC we realized constrained

F3.24.2

crystallization of ultra-thin a-Si:H sublayers within a-Si:H/a-SiNX:H multilayers and controlled the transverse and longitudinal positions of nc-Si dots to achieve three-dimensional ordered distribution of nc-Si [13-14]. In this paper, we attempt to realize two-dimensional (2D) ordered distribution of nc-Si