Elucidating the role of nitrogen plasma composition in the low-temperature self-limiting growth of indium nitride thin films

In this work, we have studied the role varying nitrogen plasma compositions play in the low-temperature plasma-assisted growth of indium nitride (InN) thin films. Films were deposited on Si (100) substrates using a plasma-enhanced atomic layer deposition (PE-ALD) reactor featuring a capacitively-coupled hollow-cathode plasma source. Trimethylindium (TMI) and variants of nitrogen plasma (N₂-only, Ar/N₂, and Ar/N₂/H₂) were used as the metal precursor and nitrogen co-reactant, respectively. In situ ellipsometry was employed to observe individual ligand exchange and plasma-assisted ligand removal events in real-time during the growth process. Only the samples grown under hydrogen-free nitrogen plasmas (Ar/N₂ or N₂-only) resulted in nearly stoichiometric single-phase crystalline hexagonal InN (h-InN) films at substrate temperatures higher than 200 °C under 100 W rf-plasma power. Varying the plasma gas composition by adding H₂ led to rather drastic microstructural changes resulting in a cubic phase oxide (c-In₂O₃) film. Combining the in situ measured growth evolution with ex situ materials characterization, we propose a simplified model describing the possible surface reactions/groups during a unit PE-ALD cycle, which depicts the highly efficient oxygen incorporation in the presence of hydrogen radicals. Further structural, chemical, and optical characterization have been carried out on the optimal InN films grown with Ar/N₂ plasma to extract film properties. Samples grown at lower substrate temperature (160 °C) and reduced/elevated rf-plasma power levels (50/150 W) displayed similar amorphous character, which is attributed to either insufficient surface energy or plasma-induced crystal damage. InN samples grown at 240 °C under 100 W rf-plasma showed clear polycrystalline h-InN layers with ∼20 nm average-sized single crystal domains exhibiting hexagonal symmetry.

Hollow-cathode plasma-generated hydrogen radicals induce crystal phase transformation from h-InN to c-In₂O₃ during plasma-enhanced atomic layer deposition using trimethyl-indium and Ar/N₂ plasma.     

Preconception Health Risks Among U.S. Women: Disparities at the Intersection of Disability and Race or Ethnicity

IntroductionPrior research has found that some preconception health risks are more prevalent among women in historically minoritized racial and ethnic groups. Preconception health risks are also increased among women with disabilities. Risks could be even greater among women who both have a disability and belong to a minoritized racial or ethnic group. The purpose of this study was to assess preconception health at the intersection of disability and race or ethnicity.MethodsWe analyzed data from the 2016 Behavioral Risk Factor Surveillance System to estimate the prevalence of health behaviors, health status indicators, and preventive healthcare receipt among nonpregnant women 18–44 years of age. We used modified Poisson regression to compare non-Hispanic White women with disabilities and women with and without disabilities in three other race/ethnicity groups (non-Hispanic Black, Hispanic, other race) to a reference group of non-Hispanic White women without disabilities. Disability status was defined based on affirmative response to at least one of six questions about difficulty with seeing, hearing, mobility, cognition, personal care, or independent living tasks. Multivariate analyses adjusted for other sociodemographic characteristics such as age and marital status.ResultsIn every racial and ethnic group, women with disabilities had a significantly higher prevalence of most preconception health risks than their counterparts without disabilities. The disparity in obesity for Black women with disabilities was additive, with the adjusted prevalence ratio (PR, 1.77; 95% confidence interval [CI], 1.57–2.00) equal to the sum of the prevalence ratios for disability alone (PR, 1.29; 95% CI, 1.19–1.41) and Black race alone (PR, 1.47; 95% CI, 1.36–1.58).ConclusionsWomen at the intersection of disability and minoritized race or ethnicity may be at especially high risk of adverse outcomes. Targeted efforts are needed to improve the health of women of reproductive age in these doubly marginalized populations.     

Atomic layer deposition of metal oxides for efficient perovskite single-junction and perovskite/silicon tandem solar cells

Aluminum-doped and undoped zinc oxide films were investigated as potential front and rear contacts of perovskite single and perovskite/silicon tandem solar cells. The films were prepared by atomic layer deposition (ALD) at low (<200 °C) substrate temperatures. The deposited films were crystalline with a single-phase wurtzite structure and exhibit excellent uniformity and low surface roughness which was confirmed by XRD and SEM measurements. Necessary material characterizations allow for realizing high-quality films with low resistivity and high optical transparency at the standard growth rate. Spectroscopic ellipsometry measurements were carried out to extract the complex refractive index of the deposited films, which were used to study the optics of perovskite single junction and perovskite/silicon tandem solar cells. The optics was investigated by three-dimensional finite-difference time-domain simulations. Guidelines are provided on how to realize perovskite solar cells exhibiting high short-circuit current densities. Furthermore, detailed guidelines are given for realizing perovskite/silicon tandem solar cells with short-circuit current densities exceeding 20 mA cm⁻² and potential energy conversion efficiencies beyond 31%.

The necessity of thin and highly doped metal oxide films is discussed for realizing efficient perovskite single and perovskite/silicon tandem solar cells.     

Postpartum Hospital Utilization among Massachusetts Women with Intellectual and Developmental Disabilities: A Retrospective Cohort Study

Objectives This study examined the risk of postpartum hospital admissions and emergency department (ED) visits among US women with intellectual and developmental disabilities (IDD). Methods We used the 2002–2012 Pregnancy to Early Life Longitudinal Data System and identified deliveries to women with and without IDD. Women with IDD (n?=?1104) or case subjects were identified from the International Classification of Diseases and Related Health Problems 9th Revision (ICD-9 CM) codes. The study primary outcome measures were any postpartum hospital admission and any ED visit during three critical postpartum periods (1–42, 43–90, and 1–365 days). We conducted unadjusted and adjusted survival analysis using Cox proportional hazard models to compare the occurrence of first hospital admission or ED visits between women with and without IDD. Results We found that women with IDD had markedly higher rates of postpartum hospital admissions and ED visits during the critical postpartum periods (within 1–42, 43–90, and 91–365 days) after a childbirth. Conclusion for Practice Given the heightened risk of pregnancy complications and adverse birth outcomes and the findings of this study, there is an urgent need for clinical guidelines related to the frequency and timing of postpartum care among new mothers with IDD. Further, this study provides evidence of the need for evidence-based interventions for new mothers with IDD to provide preventive care and routine assessments that would identify and manage complications for both the mother and the infant outside of the traditional postpartum health care framework.     

Impact of Medical Home on Health Care of Children With and Without Special Health Care Needs: Update from the 2016 National Survey of Children’s Health

Objective The medical home has been promoted as an optimal model of health care delivery for children. The purpose of this study was to examine the association between having access to a medical home and the health care experiences of children with and without special health care needs (SHCN) in the United States. Methods We analyzed data from the 2016 National Survey of Children’s Health. We modeled logistic regressions to assess associations of having access to a medical home with health care experiences for 11,392 CSHCN and 38,820 non-CSHCN. Results We found that not having access to a medical home was negatively associated with preventive medical and dental care visits, greater unmet medical and dental needs, and hospital emergency room visits. Additionally, not having access to a medical home was negatively associated with the physical and oral health among CSHCN and oral health among non-CSHCN. However, we found no significant association between improved physical health status and having access to a medical home among non-CSHCN. Conclusions Results from our analysis suggest that having access to a medical home remains key determinant of improved health care experiences by CSHCN and non-CSHCN in the United States. Our findings underscore the need to develop policies and implement a more concerted program to increase access to health care delivered under the medical home model for CSHCN and non-CSHCN. Policymakers, health care administrators and physician groups can use these findings to inform future policy decisions and service delivery reforms.