Si implant-assisted Ohmic contacts to GaN

The contact resistance, ρC, was measured for the traditional Ti/Al/Ni/Au Ohmic contact for samples implanted with Si to \u3e1020 cm-3 and annealed at 1100, 1150, 1200, or 1250°C for 2, 5 or 10 min using an AlN annealing cap. These results are compared with those for samples annealed in the same way, but were not implanted. The as-grown samples were doped to 3.56 × 1017 or 6.67 × 1016 cm-3 or were unintentionally (UI) doped. In almost all cases, ρC for the implanted sample was lower, and a record low ρC = 2.66 × 10-8 Ω cm2 was achieved for the more heavily doped implanted sample annealed at 1200 °C for 10 min. ρC decreased with the doping concentration, and for the UI samples, Ohmic contacts could be made only if the samples were implanted. The surface roughness was also measured, and it was found for an as-grown with an RMS roughness of 0.303 nm, the roughness increased from 0.623 after an 1100°C anneal to 3.197 nm after a 1250°C anneal for the implanted samples annealed for 10 min, and it increased from 1.280 nm to 5.357 nm under the same conditions for the samples that were not implanted

Changing trends in mortality among solid organ transplant recipients hospitalized for COVID-19 during the course of the pandemic.

Mortality among patients hospitalized for COVID-19 has declined over the course of the pandemic. Mortality trends specifically in solid organ transplant recipients (SOTR) are unknown. Using data from a multicenter registry of SOTR hospitalized for COVID-19, we compared 28-day mortality between early 2020 (March 1, 2020-June 19, 2020) and late 2020 (June 20, 2020-December 31, 2020). Multivariable logistic regression was used to assess comorbidity-adjusted mortality. Time period of diagnosis was available for 1435/1616 (88.8%) SOTR and 971/1435 (67.7%) were hospitalized: 571/753 (75.8%) in early 2020 and 402/682 (58.9%) in late 2020 (p \u3c .001). Crude 28-day mortality decreased between the early and late periods (112/571 [19.6%] vs. 55/402 [13.7%]) and remained lower in the late period even after adjusting for baseline comorbidities (aOR 0.67, 95% CI 0.46-0.98, p = .016). Between the early and late periods, the use of corticosteroids (≥6 mg dexamethasone/day) and remdesivir increased (62/571 [10.9%] vs. 243/402 [61.5%], p \u3c .001 and 50/571 [8.8%] vs. 213/402 [52.2%], p \u3c .001, respectively), and the use of hydroxychloroquine and IL-6/IL-6 receptor inhibitor decreased (329/571 [60.0%] vs. 4/492 [1.0%], p \u3c .001 and 73/571 [12.8%] vs. 5/402 [1.2%], p \u3c .001, respectively). Mortality among SOTR hospitalized for COVID-19 declined between early and late 2020, consistent with trends reported in the general population. The mechanism(s) underlying improved survival require further study

COVID‐19 in hospitalized lung and non‐lung solid organ transplant recipients: A comparative analysis from a multicenter study

Lung transplant recipients (LTR) with coronavirus disease 2019 (COVID-19) may have higher mortality than non-lung solid organ transplant recipients (SOTR), but direct comparisons are limited. Risk factors for mortality specifically in LTR have not been explored. We performed a multicenter cohort study of adult SOTR with COVID-19 to compare mortality by 28 days between hospitalized LTR and non-lung SOTR. Multivariable logistic regression models were used to assess comorbidity-adjusted mortality among LTR vs. non-lung SOTR and to determine risk factors for death in LTR. Of 1,616 SOTR with COVID-19, 1,081 (66%) were hospitalized including 120/159 (75%) LTR and 961/1457 (66%) non-lung SOTR (p = .02). Mortality was higher among LTR compared to non-lung SOTR (24% vs. 16%, respectively, p = .032), and lung transplant was independently associated with death after adjusting for age and comorbidities (aOR 1.7, 95% CI 1.0-2.6, p = .04). Among LTR, chronic lung allograft dysfunction (aOR 3.3, 95% CI 1.0-11.3, p = .05) was the only independent risk factor for mortality and age >65 years, heart failure and obesity were not independently associated with death. Among SOTR hospitalized for COVID-19, LTR had higher mortality than non-lung SOTR. In LTR, chronic allograft dysfunction was independently associated with mortality

Covid-19 in hospitalized lung and non-lung solid organ transplant recipients: a comparative analysis from a multicenter study.

Lung transplant recipients (LTR) with Covid-19 may have higher mortality than non-lung solid organ transplant recipients (SOTR), but direct comparisons are limited. Risk factors for mortality specifically in LTR have not been explored. We performed a multicenter cohort study of adult SOTR with Covid-19 to compare mortality by 28-days between hospitalized LTR and non-lung SOTR. Multivariable logistic regression models were used to assess comorbidity-adjusted mortality among LTR vs. non-lung SOTR and to determine risk factors for death in LTR. Of 1,616 SOTR with Covid-19, 1,051 (65%) were hospitalized including 117/159 (74%) LTR and 934/1457 (64%) non-lung SOTR (p=0.02). Mortality was higher among LTR compared to non-lung SOTR (24% vs. 16%, respectively, p=0.035) and lung transplant was independently associated with death after adjusting for age and comorbidities (aOR 1.7, 95% CI 1.0-2.6, p=0.05). Among LTR, independent risk factors for mortality included single lung transplant (aOR 2.8, 95% CI 1.0-7.7, p=0.04) and chronic lung allograft dysfunction (aOR 3.6, 95% CI 1.0-12.4, p=0.05), but not age \u3e65 years, heart failure, or obesity. Among SOTR hospitalized for Covid-19, LTR had higher mortality than non-lung SOTR. In LTR, single lung transplant and chronic allograft dysfunction were independently associated with mortality