Geometric control of diffusing elements on InAs semiconductor surfaces via metal contacts.

Local geometric control of basic synthesis parameters, such as elemental composition, is important for bottom-up synthesis and top-down device definition on-chip but remains a significant challenge. Here, we propose to use lithographically defined metal stacks for regulating the surface concentrations of freely diffusing synthesis elements on compound semiconductors. This is demonstrated by geometric control of Indium droplet formation on Indium Arsenide surfaces, an important consequence of incongruent evaporation. Lithographic defined Aluminium/Palladium metal patterns induce well-defined droplet-free zones during annealing up to 600 °C, while the metal patterns retain their lateral geometry. Compositional and structural analysis is performed, as well as theoretical modelling. The Pd acts as a sink for free In atoms, lowering their surface concentration locally and inhibiting droplet formation. Al acts as a diffusion barrier altering Pd's efficiency. The behaviour depends only on a few basic assumptions and should be applicable to lithography-epitaxial manufacturing processes of compound semiconductors in general.

HIV-associated infective native aortic aneurysms.

HIV-associated infective native aortic aneurysms (INAA) constitute a subcategory of the disease INAA. This is a very rare group of patients. The aim of this systematic literature review was to compile a description of patient characteristics with HIV-associated INAA. A systematic literature review was performed using the search terms HIV and aortic aneurysm in Ovid MEDLINE and Embase databases, on articles published between 1981 and 2022. Using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, articles were scrutinized according to a predefined protocol including age, sex, comorbidities, microbiological pathogens, CD4-count, HIV/AIDS state, aortic segment involved, treatment and outcome. Thirty-three studies, all case reports with a total of 39 patients, were included. The median age was 48 years (range 27-79), most were male n = 35 (90%), and the median follow-up was n = 6 months (range 0-63). Cardiovascular comorbidity was present in n = 1 (3%), median CD4-count was 216 (range 6-1236), and n = 12 (31%) had AIDS. The most common microbiological pathogens were Treponema pallidum, n = 12 (31%), Salmonella spp. n = 10 (26%), Mycobacterium species n = 5 (12%) and Staphylococcal spp. n = 5 (13%). The HIV-associated INAAs were localized in the abdominal aorta n = 32 (82%), in the thoracic aorta n = 5 (13%) and in the thoraco-abdominal aorta n = 2 (5%). Open surgery was performed in n = 23 (59%) patients, endovascular aortic repair n = 6 (15%), and n = 7 (18%) did not receive surgery. Infection-related complications were reported in n = 2 (7%) patients, both with postoperative development of fatal sepsis. Patients with HIV-associated INAAs were younger, had lower rate of cardiovascular comorbidity, demonstrated low CD4 counts as a measure of immunosuppression, and demonstrated diverse microbiological pathogens compared with other INAAs. Treponema pallidum and Mycobacterium spp. were common pathogens, which are very rare microbiological pathogens in other INAAs.

Improved Electrostatics through Digital Etch Schemes in Vertical GaSb Nanowire p-MOSFETs on Si.

Sb-based semiconductors are critical p-channel materials for III-V complementary metal oxide semiconductor (CMOS) technology, while the performance of Sb-based metal-oxide-semiconductor field-effect transistors (MOSFETs) is typically inhibited by the low quality of the channel to gate dielectric interface, which leads to poor gate modulation. In this study, we achieve improved electrostatics of vertical GaSb nanowire p-channel MOSFETs by employing robust digital etch (DE) schemes, prior to high-κ deposition. Two different processes, based on buffer-oxide etcher (BOE) 30:1 and HCl:IPA 1:10, are compared. We demonstrate that water-based BOE 30:1, which is a common etchant in Si-based CMOS process, gives an equally controllable etching for GaSb nanowires compared to alcohol-based HCl:IPA, thereby realizing III-V on Si with the same etchant selection. Both DE chemicals show good interface quality of GaSb with a substantial reduction in Sb oxides for both etchants while the HCl:IPA resulted in a stronger reduction in the Ga oxides, as determined by X-ray photoelectron spectroscopy and in agreement with the electrical characterization. By implementing these DE schemes into vertical GaSb nanowire MOSFETs, a subthreshold swing of 107 mV/dec is obtained in the HCl:IPA pretreated sample, which is state of the art compared to reported Sb-based MOSFETs, suggesting a potential of Sb-based p-type devices for all-III-V CMOS technologies.

Performance enhancement of GaSb vertical nanowire p-type MOSFETs on Si by rapid thermal annealing.

GaSb is considered as an attractive p-type channel material for future III-V metal-oxide-semiconductor (MOS) technologies, but the processing conditions to utilize the full device potential such as low power logic applications and RF applications still need attention. In this work, applying rapid thermal annealing (RTA) to nanoscale GaSb vertical nanowire p-type MOS field-effect transistors, we have improved the average peak transconductance (gm,peak) by 50% among 28 devices and achieved 70µSµm-1atVDS = -0.5 V in a device with 200 nm gate length. In addition, a low subthreshold swing down to 144 mV dec-1as well as an off-current below 5 nAµm-1which refers to the off-current specification in low-operation-power condition has been obtained. Based on the statistical analysis, the results show a great enhancement in both on- and off-state performance with respect to previous work mainly due to the improved electrostatics and contacts after RTA, leading to a potential in low-power logic applications. We have also examined a short channel device withLg = 80 nm in RTA, which shows an increasedgm,peakup to 149µSµm-1atVDS = -0.5 V as well as a low on-resistance of 4.7 kΩ·µm. The potential of further enhancement ingmvia RTA offers a good alternative to obtain high-performance devices for RF applications which have less stringent requirement for off-state performance. Our results indicate that post-fabrication annealing provides a great option to improve the performance of GaSb-based p-type devices with different structures for various applications.

Doping Profiles in Ultrathin Vertical VLS-Grown InAs Nanowire MOSFETs with High Performance.

Thin vertical nanowires based on III-V compound semiconductors are viable candidates as channel material in metal oxide semiconductor field effect transistors (MOSFETs) due to attractive carrier transport properties. However, for improved performance in terms of current density as well as contact resistance, adequate characterization techniques for resolving doping distribution within thin vertical nanowires are required. We present a novel method of axially probing the doping profile by systematically changing the gate position, at a constant gate length L g of 50 nm and a channel diameter of 12 nm, along a vertical nanowire MOSFET and utilizing the variations in threshold voltage V T shift (∼100 mV). The method is further validated using the well-established technique of electron holography to verify the presence of the doping profile. Combined, device and material characterizations allow us to in-depth study the origin of the threshold voltage variability typically present for metal organic chemical vapor deposition (MOCVD)-grown III-V nanowire devices.

Perspectives of Health Care Providers on the Role of Culture in the Self-Care of Patients with Chronic Heart Failure: A Qualitative Interview Study.

BACKGROUND: Self-care is important in chronic diseases such as heart failure. The cultural background of health care providers might influence their view on self-care behaviour and education they provide. The aim of this study was to describe health care providers' perceptions of the role of culture in self-care and how those perceptions shape their experiences and their practices. METHODS: A qualitative study was performed in Israel, a country with a culturally diverse population. Data were collected using semi-structured interviews with 12 healthcare providers from different cultural backgrounds. Interviews were recorded and transcribed verbatim and analysed using content analysis. RESULTS: Healthcare providers experienced cultural background influenced their patients' self-care behaviour. Perceived culture-specific barriers to self-care such as dietary traditions interfering with the recommended diet, willingness to undertake self-care and beliefs conflicting with medical treatment were identified. Healthcare providers described that they adapted patient education and care based on the cultural background of the patients. Shared cultural background, awareness and knowledge of differences were described as positively influencing self-care education, while cultural differences could complicate this process. CONCLUSIONS: Cultural-specific barriers for self-care were perceived by health care providers and they identified that their own cultural background shapes their experiences and their practices.