Ge/Si heterojunction photodetector for 1.064 μm laser pulses

Iso- and anisotype heterojunction Ge/Si photodetectors were made by depositing Ge layer onto monocrystalline Si using a vacuum evaporation technique. These detectors before and after annealing were utilized to detect 1.064 µm Nd:YAG laser pulses. The study also included determination of the optimal Ge thickness and annealing conditions. The experimental results show that the photoresponse was highly improved after classical thermal annealing and rapid thermal annealing (RTA). The voltage responsivity and signal rise time results strongly depended on the annealing type and conditions. It was found that the optimal conditions can be obtained for n-Ge/p-Si photodetector prepared with Ge 200 nm thick and treated with RTA at 500 ºC for 25 s

Overview of Tissue Engineering and Drug Delivery Applications of Reactive Electrospinning and Crosslinking Techniques of Polymeric Nanofibers with Highlights on Their Biocompatibility Testing and Regulatory Aspects

Traditional electrospinning is a promising technique for fabricating nanofibers for tissue engineering and drug delivery applications. The method is highly efficient in producing nanofibers with morphology and porosity similar to the extracellular matrix. Nonetheless, and in many instances, the process has faced several limitations, including weak mechanical strength, large diameter distributions, and scaling-up difficulties of its fabricated electrospun nanofibers. The constraints of the polymer solution's intrinsic properties are primarily responsible for these limitations. Reactive electrospinning constitutes a novel and modified electrospinning techniques developed to overcome those challenges and improve the properties of the fabricated fibers intended for various biomedical applications. This review mainly addresses reactive electrospinning techniques, a relatively new approach for making in situ or post-crosslinked nanofibers. It provides an overview of and discusses the recent literature about chemical and photoreactive electrospinning, their various techniques, their biomedical applications, and FDA regulatory aspects related to their approval and marketing. Another aspect highlighted in this review is the use of crosslinking and reactive electrospinning techniques to enhance the fabricated nanofibers' physicochemical and mechanical properties and make them more biocompatible and tailored for advanced intelligent drug delivery and tissue engineering applications.This project was made possible by NPRP13S-0126-200173 from Qatar National Research Fund (a member of Qatar Foundation) through its National Priorities Research Program granted to H. M. Younes. The statements made herein are solely the responsibility of the authors.Scopu

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Structural and electrical properties of CdO/porous-Si heterojunction

The electrical properties of CdO/porous Si/c-Si heterojunction prepared by deposition of CdO layer on porous silicon synthesized by electrochemical etching were studied. The structural, optical, and electrical properties of CdO (50:50) thin film prepared by rapid thermal oxidation were examined. X-ray diffraction (XRD) results confirmed formation of nanostructured silicon layer the full width half maximum (FWHM) was increased after etching. The dark J-V characteristics of the heterojunction showed strong dependence on etching current density and etching time. The ideality factor and saturation current of the heterojunction were calculated from J-V under forward bias. C-V measurements confirmed that the prepared heterojunctions are abrupt type .The value of built-in-potential as function of etching current density was estimated

Structural, Morphological, Chemical and Optical Properties of Porous Silicon Prepared By Electrochemical Etching

In this paper, porous silicon layers was prepared from p-type silicon with orientation (100) by electrochemical etching method , samples were anodized in a solution of 48% HF and 99% C2H2OH at 1:1 ratio and study the morphology properties of PSi samples by changing etching time (15, 17 and 20) min for fixed (11.5 mA/ cm2) current density, and imaged PSi sample in Atomic force microscopy(AFM), which shows the rough silicon surface, with increasing etching process (etching time) porous structure nucleates which leads to an increase in the depth and width (diameter) of surface pits. Consequently, the surface roughness also increases and we found that the porosity of PSi increasing with the increasing etching time. The XRD measurements has confirmed the crystallinity nature of porous silicon. A broad peak of blue emission has also confirmed by photoluminescence (PL) measurements and it has been attributed to SiHx groups which are confirmed by FTIR spectra. Chemical fictionalization during the electrochemical etching show on surface chemical composition of PSi. From the FTIR analyses showed that the Si dangling bonds of the as-prepared PSi layers have large amount of Hydrogen to form weak Si–H bonds

بناء المخطط الطاقي للمفرق الهجيني ................

In this paper we present experimental investigation of band lineup of near ideal PbS/Si heterojunction diode using I-V and C-V measurements. The C-V measurements show that the fabricated diodes were abrupt type, and the built-in potential Vui wds determined from C-2-V plot. The band offsets of A,Ec: 0.15 eV and A,Ev:0.55 eV were calculated at 300 K for conduction and valence bands, respectively. The energy band diagram of n-PbS/p-Si heterojunction was constructed. I-V measurements of different temperatures near 300K were employed to frnd the potential barrier to electron transport process across the junction.في هذا البحث تم بناء المخطط الطاقي للمفرق الهجيني نوع PbS/Si من خلال قياسات تيار – جهد وسعة – جهد . أوضحت قياسيات سعة – جهد أن الديودات المصنعة من النوع الحاد ونم تحديد مقدار جهد البناء الداخلي من خلال المنحني (1/C2) –V . كان مقدارEc Δ بحدود 0.15 eV ومقدار Δ Ev=0.55eV حيث تم حسابهما عند درجة حرارة الغرفة. تمت دراسة خصائص تيار – جهد عند درجات حرارة قريبة من درجة حرارة الغرفة لإيجاد حاجز الجهد لعملية انتقال الالكترونيات خلال منطقة الاتصا

دراسة تحليلية للانتشار المحتث بالليزر النبضي لشوائب الالومنيوم في منصهر الجرمانيوم باستخدام تقنية المطياف الكتلي للأيونات الثانوية

In this work the volume diffusion coefficients and profile distribution of Al impurities in molten germanium have been measured using secondary-iron mass spectroscopy (SIMS) technique. Diffusion is achieved with aid of Nd:Yag laser pulses. In this study it is shown that the diffusion coefficients and profile distribution of impurities are extremely sensitive to laser energy density. The calculated diffusion coefficients are ranging from 6.69 x 10"9 to 5.9 x 10~9 cm2.s'lفي هذه الدراسة تم قياس معامل وشكل انتشار شوائب الألومنيوم في منصهر الجرمانيوم باستخدام تقنية المطياف الكتلي للأيونات الثانوية، حيث تم استخدام ليزر النديميوم - ياك النبضي في عملية الانتشار المحتث . من الحسابات ظهر اًن معامل الانتشار وهيئة توزيع شوائب الألومنيوم في الجرمانيوم تعتمد بشكل كبير على كثافة طاقة نبضة الليزر، وقد أوضحت النتائج أن مقدار معامل الانتشار تراوح ما بين 6.69*10-9 -8 و 5*10-8 سم2 /