International Care programs for Pediatric Post-COVID Condition (Long COVID) and the way forward

Background: Pediatric Post-COVID-Condition (PPCC) clinics treat children despite limited scientific substantiation. By exploring real-life management of children diagnosed with PPCC, the International Post-COVID-Condition in Children Collaboration (IP4C) aimed to provide guidance for future PPCC care. // Methods: We performed a cross-sectional international, multicenter study on used PPCC definitions; the organization of PPCC care programs and patients characteristics. We compared aggregated data from PPCC cohorts and identified priorities to improve PPCC care. // Results: Ten PPCC care programs and six COVID-19 follow-up research cohorts participated. Aggregated data from 584 PPCC patients was analyzed. The most common symptoms included fatigue (71%), headache (55%), concentration difficulties (53%), and brain fog (48%). Severe limitations in daily life were reported in 31% of patients. Most PPCC care programs organized in-person visits with multidisciplinary teams. Diagnostic testing for respiratory and cardiac morbidity was most frequently performed and seldom abnormal. Treatment was often limited to physical therapy and psychological support. // Conclusions: We found substantial heterogeneity in both the diagnostics and management of PPCC, possibly explained by scarce scientific evidence and lack of standardized care. We present a list of components which future guidelines should address, and outline priorities concerning PPCC care pathways, research and international collaboration

Compensation of the sputter damage during a-Si deposition for poly-Si/SiO_x passivating contacts by ex-situ p-doping

The rf magnetron sputter deposition of a-Si during fabrication of passivating contacts based on poly-Si on top of an interfacial silicon oxide (poly-Si/SiOx) and a possible sputter damage is investigated, as it is also observed during transparent conductive oxide sputtering for heterojunction solar cells. It is shown that the high temperature anneal for partial crystallization of the sputtered a-Si has a detrimental effect on passivation quality. However, doping during partial crystallization of the a-Si layer by a POCl3-diffusion compensates this decrease of passivation quality by a field effect passivation. Moreover, a subsequent hydrogenation of the interface leads to implied open circuit voltages of up to 719 mV and saturation current densities of down to 9 fA/cm2. Furthermore, depth profiles of the dopants measured by glow discharge optical emission spectroscopy (GD-OES) and electrochemical capacitance-voltage profiling (ECV) reveal a significant difference between total (∼3.5·1021 cm−3) and electrically active (∼5·1020 cm−3) phosphorous atomic density in the poly-Si layer. From these depth profiles also a pile-up of electrically inactive phosphorous close to, but a few nanometers off the interfacial oxide was observed.publishe

Correlation between the optical bandgap and the monohydride bond density of hydrogenated amorphous silicon

In this study, a variation of the substrate temperature during plasma enhanced chemical vapor deposition of hydrogenated amorphous silicon is reported, which revealed a local minimum of the optical bandgap. It is shown, that the silicon monohydride bond density is more appropriate to describe this dependency than the commonly discussed layer properties hydrogen concentration and structural disorder. Furthermore, a high silicon monohydride bond density regime is suggested, in which the optical bandgap is independent of the bond density. This hypohesis explains previously published constant optical bandgaps under variation of the hydrogen concentration and structural disorder.publishe

Dissolution of Electrically Inactive Phosphorus by Low Temperature Annealing

AbstractIn this study we investigate the dissolution of electrically inactive phosphorus complexes by low temperature annealing after the POCl3 diffusion process. This has the immediate consequence that the existing near-surface emitter volume SRH recombination can be reduced. Thereby, a significant reduction of emitter saturation current density j0E is achieved without driving the emitter further into the silicon substrate. For short-term temperature treatments well below the POCl3 diffusion temperature, a reduction of up to -60 fA/cm2 has been achieved. This study increases our understanding of the formation and dissolution of electrically inactive phosphorus complexes during post-annealing processes

Enhanced oxidation of thermally grown SiO₂ due to P precipitates

Previous studies of thermal oxidation on a doped structure showed that growth of thermal SiO2 depends on the charge carrier concentration. Here we show that growth behavior of a thermal SiO2 layer also depends strongly on the emitter’s electrically nonactive P concentration. Experimental data show that an increase in P precipitate concentration has a significant influence on the growth kinetics of thermally grown SiO2 layers. Despite constant charge carrier concentration in the emitter, an increase in growth rate up to a factor of 2 was measured in samples with increased inactive P concentration. Quantitative elemental analysis of the thermally grown SiO2 layers further shows that the SiO2 composition can be strongly influenced by the Si substrate’s inactive P concentration.publishe

Influence of the Carbon Concentration on ( p ) Poly-SiC x Layer Properties With Focus on Parasitic Absorption in Front Side Poly-SiC x /SiO x Passivating Contacts of Solar Cells

Passivating contacts based on polycrystalline silicon (poly-Si) on an interfacial oxide are limited by parasitic absorption, which may be reduced by incorporation of foreign elements in the poly-Si layer. In this study, the influence of carbon incorporation in the concentration range of 6.9-21.5 at% on boron-doped polycrystalline silicon carbide (poly-SiCx) layer properties is investigated and interpreted in the context of an application as full-area passivating contact on the front side of a solar cell. For constant annealing parameters, higher carbon concentrations reduce the crystallinity of the layers. A high crystallinity in turn is confirmed to be a key parameter for the application in a solar cell as it ensures both low resistivity as well as low parasitic absorption. Low recombination current densities in the range of 7.2-12.2 fA/cm 2 are determined for all layers on interfacial oxides on planar surfaces, whereas the differences are rather related to variations in the boron concentration than to the carbon concentration or the deposition parameters. A reduction of the (p) poly-SiCx layer thickness down to 10 nm would yield a parasitic absorption current density of 1.13 ± 0.13 mA/cm 2 . Using this value and the lowest measured recombination current density, a simple model predicts a theoretical solar cell efficiency limit of 26.7 ± 0.2%

International care programs for Pediatric Post-COVID Condition (Long COVID) and the way forward

Background: Pediatric Post-COVID-Condition (PPCC) clinics treat children despite limited scientific substantiation. By exploring real-life management of children diagnosed with PPCC, the International Post-COVID-Condition in Children Collaboration (IP4C) aimed to provide guidance for future PPCC care. Methods: We performed a cross-sectional international, multicenter study on used PPCC definitions; the organization of PPCC care programs and patients characteristics. We compared aggregated data from PPCC cohorts and identified priorities to improve PPCC care. Results: Ten PPCC care programs and six COVID-19 follow-up research cohorts participated. Aggregated data from 584 PPCC patients was analyzed. The most common symptoms included fatigue (71%), headache (55%), concentration difficulties (53%), and brain fog (48%). Severe limitations in daily life were reported in 31% of patients. Most PPCC care programs organized in-person visits with multidisciplinary teams. Diagnostic testing for respiratory and cardiac morbidity was most frequently performed and seldom abnormal. Treatment was often limited to physical therapy and psychological support. Conclusions: We found substantial heterogeneity in both the diagnostics and management of PPCC, possibly explained by scarce scientific evidence and lack of standardized care. We present a list of components which future guidelines should address, and outline priorities concerning PPCC care pathways, research and international collaboration