Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear t...Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear track chemical etching data bank was developed.Three regimes of CR-39 bulk etching were identified.Regime I spans etchant concentrations from 2 to 12 N.Regime II spans concentrations from 12 to 25 N.We call this the dynamic bulk etching regime.Regime III is for concentrations greater than 25 N.In this regime,the bulk etch rate is saturated with respect to the etchant concentration.This classification is discussed and explained.The role of ethanol in NaOH-based etchants is explored and discussed.A parameter called the “reduced bulk etch rate” is defined here,which helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant.The bulk etch rate shows a natural logarithmic dependence on the density of ethanol in the etchant.展开更多
In this study, we used strippable LR 115 type 2 which is a Solid State Nuclear Track Detector (SSNTD) widely known for radon gas detection and measurement. The removed thickness of the active layer of samples of this ...In this study, we used strippable LR 115 type 2 which is a Solid State Nuclear Track Detector (SSNTD) widely known for radon gas detection and measurement. The removed thickness of the active layer of samples of this SSNTD, were determined by measuring the average initial thickness (before etching) and residual thickness after 80 to 135 minutes chemical etching in the standard conditions, using an electronic comparator. These results allowed the calculation of the bulk etch rate of this detector in a simple way. The mean value obtained is (3.21 ± 0.21) μm/h. This value is in close agreement with those reported by different authors. It is an important parameter for alpha track counting on the sensitive surface of this polymeric detector after chemical etching because track density depends extremely on its removed layer. This SSNTD was then used for environmental radon gas monitoring in Côte d’Ivoire.展开更多
Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pr...Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pressure and working temperature. The etching process of Si3N4 is studied by inductively coupled plasma (ICP) with a gas mixture of SF6 and O2. The influence of the technique parameters, such as ICP power, DC bias, gas composition, total flow rate, on the etching selectivity of Si3N4/EPG533 which is used as a mask layer and the etching rate of Si3N4 is studied, in order to get a better etching selectivity of Si3N4/EPG533 with a faster etching rate of Si3N4. The optimized process parameters of etching Si3N4 by ICP are obtained after a series of experiments and analysis. Under the conditions of total ICP power of 250 W, DC bias of 50W, total flow rate of 40 sccm and O2 composition of 30%, the etching selectivity of 2.05 can be reached when Si3N4 etching rate is 336 nm/min.展开更多
文摘Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear track chemical etching data bank was developed.Three regimes of CR-39 bulk etching were identified.Regime I spans etchant concentrations from 2 to 12 N.Regime II spans concentrations from 12 to 25 N.We call this the dynamic bulk etching regime.Regime III is for concentrations greater than 25 N.In this regime,the bulk etch rate is saturated with respect to the etchant concentration.This classification is discussed and explained.The role of ethanol in NaOH-based etchants is explored and discussed.A parameter called the “reduced bulk etch rate” is defined here,which helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant.The bulk etch rate shows a natural logarithmic dependence on the density of ethanol in the etchant.
文摘In this study, we used strippable LR 115 type 2 which is a Solid State Nuclear Track Detector (SSNTD) widely known for radon gas detection and measurement. The removed thickness of the active layer of samples of this SSNTD, were determined by measuring the average initial thickness (before etching) and residual thickness after 80 to 135 minutes chemical etching in the standard conditions, using an electronic comparator. These results allowed the calculation of the bulk etch rate of this detector in a simple way. The mean value obtained is (3.21 ± 0.21) μm/h. This value is in close agreement with those reported by different authors. It is an important parameter for alpha track counting on the sensitive surface of this polymeric detector after chemical etching because track density depends extremely on its removed layer. This SSNTD was then used for environmental radon gas monitoring in Côte d’Ivoire.
文摘Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pressure and working temperature. The etching process of Si3N4 is studied by inductively coupled plasma (ICP) with a gas mixture of SF6 and O2. The influence of the technique parameters, such as ICP power, DC bias, gas composition, total flow rate, on the etching selectivity of Si3N4/EPG533 which is used as a mask layer and the etching rate of Si3N4 is studied, in order to get a better etching selectivity of Si3N4/EPG533 with a faster etching rate of Si3N4. The optimized process parameters of etching Si3N4 by ICP are obtained after a series of experiments and analysis. Under the conditions of total ICP power of 250 W, DC bias of 50W, total flow rate of 40 sccm and O2 composition of 30%, the etching selectivity of 2.05 can be reached when Si3N4 etching rate is 336 nm/min.
