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In this work we designed, fabricated and assessed a p+/n/n+ structure which constitute the basis and the core part of the n-type silicon solar cells. The process of fabrication is based on the co-diffusion of pre-deposited phosphorus and boron. It consists of carrying out simultaneously in one single high temperature step the diffusion of both boron and phosphorus of the p+ emitter and pre-deposited n+- back surface field (BSF), respectively. The first step was the pre-formation of the n+-BSF in a POCl3 furnace system. After depositing the silicon nitride film onto the wafers rear side as a diffusion barrier to protect them from being boron doped, the wafers underwent an alkaline bath to etch the phosphorus layer of the front side. Onto this latter we used a boron source paper sheets to create a p+ emitter (preform source) simultaneously with n+-BSF drive-in step. This co-diffusion process was carried out at a temperature of 930 °C in a quartz tube devoted to this purpose. The resulting structure has a sheet resistance of 49 Ω/□ and 39 Ω/□ for emitter and BSF, respectively, corresponding to junction depths of 0.40 μm and 0.55 μm. The dopants surface concentrations are of 1.14 E20 atoms. cm−3 and 6.20 E19 atoms. cm−3 for emitter and BSF, respectively. This p+/n/n+ structure was used to fabricate solar cells after passivating the emitter and screen printing the front and rear side metallic contacts. A short circuit current density of 31.60 mA/cm2, an open circuit voltage of 555 mV and an efficiency of 10.70% was measured indicating that our non-optimized fabrication process and the resultant device is viable. [ABSTRACT FROM AUTHOR]

The SiN/SiO2 stack is widely used to passivate the surface of n-type monocrystalline silicon solar cells. In this work, we have undertaken a study to compare the stack layer obtained with SiO2 grown by both rapid thermal and chemical ways to passivate n-type monocrystalline silicon surface. By varying the plateau time and the plateau temperature of the rapid thermal oxidation, we determined the parameters to grow 10 nm thick oxide. Two-step nitric acid oxidation was used to grow 2 nm thick silicon oxide. Silicon nitride films with three refractive indices were used to produce the SiN/SiO2 stack. Regarding this parameter, the minority carrier lifetime measured by means of QSSPC revealed that the refractive index of 1.9 ensured the best passivation quality of silicon wafer surface. We also found that stacks with nitric acid oxidation showed definitely the best passivation quality. In addition to produce the most efficient passivation, this technique has the lowest thermal budget. [ABSTRACT FROM AUTHOR]

The objective of this study is to characterize purebred Arab mares' milk through monitoring its physicochemical and microbiological composition during different lactation stages and to test its ability to coagulate. Sixteen purebred Arabian mares were selected among 45 mares with approximately the same foaling dates. Milk samples were collected once a week for each mare during 4 months of lactation and analysed in three replicates for physicochemical composition, nitrogen fractions, somatic cell count and total bacterial count. Coagulation assays were carried out in triplicates on fresh mare's milk using increasing doses of calf rennet, starter ( Streptococcus thermophilus ) and CaCl 2 . Arab mare's milk is characterized by an alkaline pH, low-fat and protein contents and high lactose content. The somatic cell and bacterial counts are very low, indicating good health status of mares. Fat and protein contents decreased as the stage of lactation progressed. However, as lactation number increased, fat level tended to increase while protein level tended to decrease. Clotting assays proved that it is possible to coagulate Arabian mare's milk using appropriate doses of calf rennet and starter, while respecting the coagulation procedures and parameters., Competing Interests: Conflict of interestThe authors declare that they have no conflict of interests., (© Association of Food Scientists & Technologists (India) 2021.)