The results of X-ray, scanning electron microscopy and atomic force microscopy studies of near-surface regions of (111) Hg_{1-x}Cd_{x}Te (x = 0.223) structures are presented. These structures were obtained by low-energy implantation with boron and silver ions. TRIM calculation of the depth dependences of impurity concentration and implantation-induced mechanical stresses in the layer near-surface regions has revealed that the low-energy implantation of HgCdTe solid solution with elements of different ionic radiuses (B^{+} and Ag^{+}) leads to the formation of layers with significant difference in thickness (400 nm and 100 nm, respectively), as well as with maximum mechanical stresses differing by two orders of magnitude (1.4 × 10^3 Pa and 2.2 × 10^5 Pa, respectively). The structural properties of the Hg_{1-x}Cd_{x}Te epilayers were investigated using X-ray high-resolution reciprocal space mapping.
The degree of the biocompatibility of polycarbonate (PC) polymer used as biomaterial can be controlled by surface modification for various biomedical engineering applications. In the past, PC samples were treated by excimer laser for surface reorganization however associated process alteration of bulk properties is reported. Extreme ultraviolet radiation can be employed in order to avoid bulk material alteration due to its limited penetration. In this study, a 10 Hz laser-plasma EUV source based on a double-stream gas-puff target irradiated with a 3 ns and 0.8 J Nd:YAG laser pulse was used to irradiate PC samples. The PC samples were irradiated with different number of EUV shots. Pristine and EUV treated samples were investigated by scanning electron microscopy and atomic force microscopy for detailed morphological characterization of micropatterns introduced by the EUV irradiation. Associated chemical modifications were investigated by X-ray photoelectron spectroscopy. Pronounced wall-type micro- and nanostructures appeared on the EUV modified surface resulting in a change of surface roughness and wettability.
Nitride-based thin-film materials have become increasingly important for the high brightness light-emitting diode applications. The improvements in light extraction and lower power consumption are highly desired. Although the internal quantum efficiency of GaN-based LED has been relatively high, only a small fraction of light can be extracted. In this study, a new design of two-dimensional photonic crystal array has been prepared on the top transparent contact layer of indium-tin oxide film to improve the light extraction efficiency using focused ion beam. The acceleration voltage of the Ga dual-beam nanotechnology system SMI 3050 was 30 kV and the ion beam current was 100 pA. The cylindrical air holes had the diameter of 150 nm and depth of 100 nm. The micro photoluminescence analysis results showed that the light output intensity could be 1.5 times of that of the non-patterned control sample. In addition, the structural damage from the focused ion beam drilling of GaN step could be eliminated. The excellent I-V characteristics have been maintained, and the external light extraction efficiency would be still improved for the LED devices.
The surface modification of polyethylene terephthalate (PET) polymer films has been performed by irradiation of extreme ultraviolet photons to investigate the effect of surface structuring on wettability control. For biomedical engineering applications, surface structuring and wettability control of PET films could enhance the polymer biocompatibility by promoting cell adhesion and consequently proliferation. The PET films are irradiated with laser plasma extreme ultraviolet source based on double stream gas puff target under different environments. The extreme ultraviolet modified PET film surfaces are characterized by atomic force microscopy and WCA goniometer. The extreme ultraviolet surface modification resulted in the formation of nano- and microstructuring on the polymer surfaces. The surface structuring consequently increased WCA making the PET surfaces more hydrophobic. The results demonstrate the direct relationship between surface roughness and hydrophobicity for extreme ultraviolet modified PET samples.
This work is related to a novel approach of providing some new generation ultrastable (> 50 years), ultrahigh density (> 1 Tbit/sq.in.) data storage for archival applications. We used ion-implantation to write nanoscale data into hydrogenated amorphous silicon carbide (a-SiC:H) films. Wide bandgap a-SiC:H samples, Ga^{+} focused ion beam implanted, have been prepared. A range of samples has been focused ion beam patterned under different implantation conditions, with emphasis on different substrate temperatures (typically from 0C temperature to around room temperature). Some of the room temperature implanted samples were further annealed at + 250C in vacuum. The focused ion beam patterned samples were then analysed using near-field techniques, like atomic force microscopy, to define optimum implantation conditions and the resulting consequences for archival data storage applications. The atomic force microscopy analysis of Ga^{+} focused ion beam implanted a-Si_{1-x}C_{x}:H samples at room temperature and at 0C revealed an increase of both the depth and the width of the individual lines within the focused ion beam written patterns at the lower temperature, as a result of an increased ion beam induced sputtering yield, in good agreement with the previous results for the case of Ga^+ broad beam implantation in a-Si_{1-x}C_{x}:H and again suggesting that the best conditions for optical data storage for archival storage applications would be using Ga^+ ion implantation in a-SiC:H films with an optimal dose at room temperatures. Similarly, the atomic force microscopy results confirm that no advantage is expected to result from post-implantation annealing treatments.
During the last two decades, the development of laboratory scale extreme ultraviolet sources has been intensified due to growing interest in use of extreme ultraviolet photons for various applications in science and technology. In this study, we present a potential application of extreme ultraviolet sources for surface modification of polymers to be used as substrates for cancer cell identification. The surface modification of polytetrafluoroethylene (PTFE) polymer samples was performed by a lab scale compact laser-plasma extreme ultraviolet source based on a double-stream gas-puff target. The gas target was irradiated with a 3 ns/0.8 J Nd:YAG laser pulse at 10 Hz. Reference HCV29 non-malignant transitional epithelium and T24 bladder cancer cells adhesion and proliferation studies on pure and extreme ultraviolet sources modified PTFE surfaces were performed. The extreme ultraviolet modified surfaces demonstrated regular increase in cancer cell proliferation comparing to pristine sample. Initial results indicate that extreme ultraviolet treated substrates can facilitate the identification of cancer cells.
Well-controlled method of Si nanopattern definition - pattern definition by edge oxidation have been presented. The technique is suitable for fabrication of narrow paths of width ranged from several tens of nm to several μm by means of photolithography equipment working with μm-scale design rules. Process details influencing a shape of the Si pattern have been discussed. SEM examinations have been presented.
The method of metal-assisted chemical etching produces a porous silicon layer. Palladium particles are deposited on both: multi-crystalline and Czochralski grown mono-crystalline Si wafers by immersing them in PdCl_{2} solution for 1 to 3 min. X-ray photoelectron spectroscopy analysis of Pd clusters shows a decrease in Pd metal fraction by prolonged immersion time t from F_{Pd} = 71.2% for t = 1 min to F_{Pd} = 61.4% for t = 3 min due to Pd oxidation process. Porous silicon forms by metal-assisted chemical etching in a HF:H_{2}O_{2} solution for 1 to 3 min. Photoluminescence of metal-assisted chemical etched samples exhibits the peak with a maximum of t at λ=650 nm independent of the etching time. Simultaneously, the intensity of the photoluminescence spectra strongly decreases for extended etching time t = 3 min. This behavior is attributed to increasing layer macroporosity, which strongly reduces amount of light emitting nanocrystallites.
Growth on deeply patterned substrates, i.e. on pillars instead of a continuous substrate, is expected to be very promising to get crack free epilayers on wafers without any bowing. We report here on a structural investigation of GaAs MBE deposited on patterned (001) offcut Si, consisting of pillars 8 μm high and 5 to 9 μm wide, to check mostly the behaviour of the threading dislocations. It is found that only very rarely they propagate up to the GaAs top that will serve as active region in devices. Twins were also detected which sometimes reached the topmost part of GaAs. However, as twins have no associated dangling bonds, they should not be electrically active. Rare antiphase boundaries exist at the interface, hence not harmful for device operation.
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