Different morphology aspects of n-type porous silicon

Fractal microstructures of light-emitting porous silicon films

“…2 suggest that the microstructures of the 23-mm-thick PS film be fractals. At this point, our results agree with the simulated results in literature [13][14][15][16][17]. As the magnification increases from 1000 in Fig.…”

“…On the other hand, computer simulation on PS formation was performed by Aleksandrov and Novikov [14] while fractal models on the pore formation in PS films were proposed by Aroutiounian et al [15] and by Makushok et al [16], respectively. All these studies showed that the microstructures of the whole PS network are characteristic of fractals [13][14][15][16][17]. Because the fractal microstructures of a PS network could pose significant effects on its physical properties [9,10], it would be important to perform a detailed investigation on the microstructures of a whole PS network.…”

“…From electron microscopy 4data, it was concluded that the sizes of individual silicon crystallites in PS films were in the order of nanometers [5][6][7][8]. When the whole PS network was taken into consideration, recent studies demonstrated that the microstructures of the whole PS network exhibit fractal features [9][10][11][12][13][14][15][16][17]. On one hand, the fractal features of the microstructures of a PS network were supported by experiments such as the ac conductivity in a low-frequency regime [9], the photoluminescence spectroscopy [10,11], the hydrogen concentration measurements [12], and the atomic force microscopy [13], respectively.…”

Correlation of excitation-wavelength dependent photoluminescence with the fractal microstructures of porous silicon

“…The fractal microstructures can give a solution to the size distribution problem in porous silicon film. In literature, the fractal microstructures were reported for the entire network of porous silicon [14][15][16][17][24][25][26][27]. Diffusion-limited aggregation is the process in which randomly walking particles come together to form aggregates and networks [28], and it has become one of the most important models of fractal growth [29].…”

Formation of micrometer-sized electrical contacts on light-emitting porous silicon films

“…Evaporation of a metal (i.e., gold, silver, or aluminum) in a vacuum evaporator is generally exploited to deposit electrical contacts onto the PS films. Unfortunately, both the fractal nature of the rough surfaces of PS films [6][7][8][9][10] and the densely distributed micropores in the PS films make the physically-evaporated electrical contacts weak in mechanical strengths and poor in electrical conductivity. Therefore, it will be important to form electrical contacts in high quality on the surfaces of PS films.…”