CF_4/Ar/O_2等离子体对熔石英元件的修饰工艺

采用感应耦合等离子体刻蚀技术,以CF4/Ar/O2为反应气体对熔石英元件表面进行修饰,研究并分析了CF4和Ar流量对刻蚀速率、熔石英表面粗糙度和微观形貌的影响。结果表明,CF4化学刻蚀与Ar的物理轰击对熔石英样品表面修饰效果存在一定竞争关系,当它们达到平衡时表面粗糙度最小。通过对不同流量气体刻蚀过后熔石英表面粗糙度和光学显微形貌分析获得了较为理想的气流量配比,该研究为反应等离子体修饰熔石英光学元件以获得较高光学性能提供工艺参考。     

CF4/Ar/O2等离子体对熔石英元件的修饰工艺

采用感应耦合等离子体刻蚀技术,以CF4/Ar/O2为反应气体对熔石英元件表面进行修饰,研究并分析了CF4和Ar流量对刻蚀速率、熔石英表面粗糙度和微观形貌的影响。结果表明,CF4化学刻蚀与Ar的物理轰击对熔石英样品表面修饰效果存在一定竞争关系,当它们达到平衡时表面粗糙度最小。通过对不同流量气体刻蚀过后熔石英表面粗糙度和光学显微形貌分析获得了较为理想的气流量配比,该研究为反应等离子体修饰熔石英光学元件以获得较高光学性能提供工艺参考。     

Time-resolved luminescence from annealed synthetic quartz under 525 nm pulsed green light stimulation

The influence of annealing on lifetimes has been studied in synthetic quartz annealed at temperatures up to 800°C using time-resolved optical stimulation in the range 20–200°C. Luminescence was stimulated using pulsed 525 nm light-emitting-diodes. There is an increase with annealing temperature in the lifetime measured at 20°C for samples annealed beyond 500°C. Further, lifetimes decrease with measurement temperature in a manner consistent with the thermal quenching of luminescence.     

Oxygen (O6+) ion beam irradiation effects on etching parameter in lexan polymeric track detector

The polymer Lexan was irradiated to 80MeV O⁶⁺ ion beam using the 15UD pelletron at Inter University Accelerator Centre, New Delhi. The ion fluence ranging from 10¹¹ to 3 × 10¹² ions/cm² has been used to study the dose effects of irradiation on Lexan. By using the etching technique, it is observed that the bulk etch rate of the sample increases with increasing the ion influence, while the activation energy associated with it show a decreasing trend which can be explained on the basis of polymer degradation.      

Stiffness properties of porous silicon nanowires fabricated by electrochemical and laser-induced etching

Nanowires with dimensions of few nanometers were formed on the whole etched surface. The optical analysis of silicon nanostructures was studied. Blue shift luminescence was observed at 660 nm for PS produced by electrochemical etching, and at 629 nm for laser-induced etching. PS produced a blue shift at 622 nm using both etching procedures simultaneously. X-ray diffraction (XRD) was used to investigate the crystallites size of PS as well as to provide an estimate of the degree of crystallinty of the etched sample. Refractive index, optical dielectric constant, bulk modulus and elasticity are calculated to investigate the optical and stiffness properties of PS nanowires, respectively. The elastic constants and the short-range force constants of PS are investigated.     

Dose-dependent optically stimulated luminescence of synthetic quartz at room temperature

Physical conditions such as annealing temperature, duration of annealing, ionizing radiation, etc., play a significant role in the applications of optically stimulated luminescence (OSL) dating as well as OSL dosimetry. Many efforts are made to understand the effect of these physical parameters on quartz specimens owing to its use in such applications. Such factors induce changes in OSL decay pattern. The definite correlation between color centers and luminescence sensitivity can be established on account of such pre-treatments to the specimen.The purpose of present investigations is to study the effect of ionizing radiation under identical physical conditions on OSL properties measured at room temperature. The shapes of decay curve and dose-response data are considered for this purpose. This study can reveal the changes in color centers in response to the pre-conditions to the specimen. It was found that the OSL decay remains slow and OSL properties change systematically with the rise in beta dose up to a critical dose; however, it changes the pattern when the beta exposure to the specimen was increased higher than the critical dose. This critical dose was found to be different for different temperature of annealing. The shape of decay curve up to the critical dose was also studied by considering the difference of OSL intensities between two successive durations from the observed OSL decay data. The results are explained based on the changes in available shallow traps during OSL measurement at room temperature with changes in pre-conditions to the specimens. The results also have been confirmed with the corresponding changes in ESR signals.     

Influence of pre-measurement thermal treatment on OSL of synthetic quartz measured at room temperature

Much effort has been made to study the influence of pre-measurement thermal treatment and ionizing radiation on quartz specimens owing to its use in a large number of applications. Optically stimulated luminescence (OSL) being a structured and sensitive phenomenon promises to correlate the responsible color center and luminescence emission. OSL studies on quartz with such conditions can reveal many significant results.The aim of the present investigation is to understand the effect of annealing temperature on OSL characteristics of synthetic quartz recorded at room temperature. At identical annealing duration and β-dose, the shape of OSL decay curve remains non-exponential; when specimens annealed at lower temperature (∼400 °C). The shape of decay curve changes to exponential in nature along with rise in OSL intensity when the specimen was given higher temperature of annealing (>400 °C). The effects of such protocol on pattern of OSL sensitivity as well as area under the OSL decay curve are also presented here. The presence of shallow traps, when OSL decay curve was recorded at room temperature seems to be responsible for the changes in OSL pattern. The influence of shallow traps is attributed to non-exponential decay of OSL recorded at room temperature.     

Effect of high gamma dose on the PADC properties

The effect of the properties of PADC nuclear track detectors after exposure to high doses of gamma absorbed doses up to 5×10⁵ Gray (50 Mrad) were studied. The gamma source was a 9.03 PBq (244 KCi), Co-60 source. Results indicate that each of the bulk etch rate (V_b), the tracks etch rate (V_t) and the sensitivity (V) of the detectors increases with the high gamma absorbed dose, but there is a drop in these parameters at the low gamma absorbed dose. Signs of surface roughness were observed by increasing the gamma absorbed doses and changes in color observed for doses larger than 2×10⁵ Gray. The temperature of detectors during irradiation time reached 41°C. The fission fragment tracks (from Cf-252 source) disappeared quickly within the etching time (minutes) for total absorbed doses greater than 3×10⁵ Gray due to their high bulk etch rate.     

Intercomparative study of the detection characteristics of the CR-39 SSNTD for light ions: Present status of the besancon-dresden approaches

For the last few years, the Besançon and Dresden teams have been working in a parallel way on light ion (protons and alphas) registration characteristics for the CR-39 SSNTD. Even if the two groups use different approaches, the main part of both investigations concerns the study of the track etch rate (V_T) and the consequences of the obtained results, which have provided us with greater understanding of detection limits.

After recalling the methods used to determine the V_T from both teams, will show how fundamental datal related to the registration properties of the CR-39 detector can be extracted. Indeed, the knowledge of an analytical relation for the V_T enables the relationship between this velocity and the primary deposited energy to the examined with respect to the same spatial variable (the instantaneous depth of penetration (x) of the incoming particle). According to experimental uncertainties, the Bragg peak of the primary ionization coincides within a very close range with the maximum of the V_T. Moreover, if increasing the etching parameters (C, T) increases the maximum V_T value, these changes do not affect its position with respect to the instantaneous depth of penetration.

Taking into account the reduced etch rate, the Dresden team found that both protons and alphas exhibit the same behavior when this rate is plotted versus the primary energy deposition rate. As a consequence, the corresponding reduced etch rate is always identical no matter what type of particle deposits a given amount of energy (e.g. proton or alpha). The Besançon team has corroborated the results obtained by the Dresden group for alphas and have extended the study to various etching conditions. From these results, the sensitivity of the CR-39 SSNTD is obtained in terms of critical LET and leads to a very low energy threshold for alpha particles. We will see throughout this paper that the lower threshold does not seem to depend on the etching parameters.     

化学腐蚀法制作SERS活性衬底

本文给出一种简便的方法——化学腐蚀法,用来制备具有SERS活性的衬底。用这种方法制作的银片衬底,增强因子最大为4×10⁴,而且其SERS特性与腐蚀剂、腐蚀时间有关。同经氧化-还原过程垂处理之银片用化学沉积法制得的眼镜相比较,化学腐蚀之银片衬底增强效果较差。     

Chemical etching investigation of polycrystalline p-type 6H-SiC in HF/Na2O2 solutions

In this work, an experimental study on the chemical etching reaction of polycrystalline p-type 6H-SiC was carried out in HF/Na₂O₂ solutions. The morphology of the etched surface was examined with varying Na₂O₂ concentration, etching time, agitation speed and temperature. The surfaces of the etched samples were analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) Fourier transform infrared spectroscopy (FT-IR) and photoluminescence. The surface morphology of samples etched in HF/Na₂O₂ is shown to depend on the solution composition and bath temperature. The investigation of the HF/Na₂O₂ solutions on 6H-SiC surface shows that as Na₂O₂ concentration increases, the etch rate increases to reach a maximum value at about 0.5 M and then decreases. A similar behaviour has been observed when temperature of the solution is increased. The maximum etch rate is found for 80 °C. In addition, a new polishing etching solution of 6H-SiC has been developed. This result is very interesting since to date no chemical polishing solution has been developed on the material.     

Track etch velocity and chemical damages induced by ions in a cellulose nitrate detector

We sum up here the results obtained on a cellulose nitrate detector (LR 115). LR 115 was irradiated with ions from proton and oxygen ions in the energy range 1–10 MeV/amu. Each irradiated sample consisted of a stack of several detectors (about 20–30) each thick. So chemical damages were studied according to the energy lost in each detector. Broken bonds were identified and quantified using infrared spectroscopy. In the same time we develop the same approach as proposed by Katz R. for the nuclear emulsion response. This approach is based on the hit theory, where the hits are produced by the secondary electrons removed by the incoming ion. Using this approach, neglecting any differences in the initial electron energy spectra and in the temporal aspect of energy deposition, it is surprising to simulate, with the very same parameters, the chemical cross sections from protons and oxygen ions.     

Fabrication of superhydrophobic surfaces on engineering material surfaces with stearic acid

Via a simple wet chemical etching followed by stearic acid modification, the presence of synergistic binary structures at micro- and nanometer scales and stearic acid bestows superhydrophobic property on steel and aluminum alloy surfaces. The as-prepared surfaces show superhydrophobic not only for pure water but also for corrosive liquids such as acid, basic and salt solutions. The stable superhydrophobicity of steel and aluminum alloy surfaces will extend their applications as engineering materials.     

Optimum parameters to etch Nd:YAG crystals with orthophosphoric acid H3PO4

Subsurface flaws, which determine the fracture strength of crystals, can be removed by the aid of chemical etching. Above a temperature of 200°C orthophosphoric acid H₃PO₄ is an efficient etchant for yttrium aluminium garnets. However, at these temperatures the etchant decomposes into its related phosphoric acids which show negligible etching rates for garnets. It takes a long time to warm up a large volume of acid and the etchant is decomposed for the most part already before the optimum temperature is reached. We show that efficient etching is achieved when the samples are in the bath already during the warm-up phase and specify the parameters for the optimum etch process.     

Fabrication of glass micro-prisms using ultra-fast laser pulses with chemical etching process

In this study, a new process of glass micro-prism structures is investigated by an ultra-fast laser irradiation with chemical etching process. The ultra-fast laser is employed by an all-in-one femtosecond laser (FS-laser) system with the amplifier as an excitation source for patterning the structures. Here, the center wavelength of laser is frequency-doubled to 517 nm. Besides, the repetition rate and pulse width of laser are 100 kHz and 350 fs, respectively. First, the embedded gratings of glass with different pitches can be fabricated using a FS-laser process. Afterwards, the glass samples are placed in the hydrofluoric acid (HF) solution for 15 min to develop structures. Finally, the results of this study demonstrated that the V-cut micro-prisms are successfully formed by controlling etching concentration between intrinsic glass material and modified areas.