Development Of N-Type Spin-On Dopant For Silicon Devices

In this research, works are focused on the preparation of n-type spin-on dopant (SOD) using sol-gel technology. The main aim of this research is to prepare n-type SOD with doping concentration in the range of 1016 to 1020 cm-3. Di dalam penyelidikan ini, kerja-kerja lebih difokuskan kepada penyediaan pendopan putaran jenis n (SOD) menggunakan teknologi sol-gel. Tujuan utama penyelidikan ini adalah untuk menyediakan SOD dengan kepekatan pendopan di antara 1016 kepada 1020 sm-3

Investigation of bandgap energies of a single phase Zn(₁₋ₓ)CuₓO nanoparticles / Suraya Ahmad Kamil … [et al.]

ZnO nanostructures are extensively studied due to their attractive characteristics and behaviour with wide band gap (3.4 eV) and large exciton binding energy (60 meV) Recently, there have been a lot of interests in studying modified ZnO nanostructures. The prospect of magnetically controlled operation of semiconductor devices has provoked intensive research to develop transition metal doped wide-band-gap semiconductors,i.e. diluted magnetic semiconductors (DMS) with room temperature ferromagnetism. Among transition metals, Cu is an especially interesting dopant because that Cu-related compounds are not strongly ferromagnetic. Transition metal-doped ZnO offers the potential for realizing room temperature operation of active spintronic devices as well as rich and fascinating fundamental physics

Ultrafast laser plasma doping of rare earth ions for optical waveguiding applications

The work presented here is to introduce and investigate a novel material and a fabrication technique for an Er3+ ion doped waveguide amplifier (EDWA) on a silicon platform. EDWA performance strongly depends on the erbium concentration and the nature of the host material. There are two materials studied for this work. For the first material, TeO2-ZnO-Na2O-Er2O3 (Er-TZN) is doped into the silica-on-silicon (SOS) substrate surface, and for the second material, Er-TZN is doped into the surface of Si3N4-on-silicon. For the first material, the mixing of Er-TZN with SiO2 produces a homogeneous layer which has the potential to be used for EDWA applications. The fabrication is carried out using a novel technique which is named ultrafast laser plasma doping (ULPD). In this technique, the Er-TZN target is bombarded using a femtosecond laser and the interfacial reaction between a high energy plasma plume and heated silica-on-silicon substrate results in a highly dense erbium doped silicate that is referred to as erbium-doped tellurite modified silica (EDTS). The success of this EDTS resulted in this work being extended to produce two types of a channel waveguide, i.e. diffused and ridge waveguide. However, for the diffused waveguide, the attempt to fabricate this type of waveguide failed to produce satisfactory results because it is believed that the metal mask moved during the fabrication process. For ridge waveguide, etching results still do not show satisfactory output. Therefore, further optimisation is needed to accomplish a practical optical waveguide. On the other hand, the doping of Er-TZN into Si3N4 which is also prepared using the ULPD technique is less successful compared to SiO2 because the doped layer exhibits inhomogeneous material distribution although various process parameters have been tried. Failure to obtain a layer like EDTS is probably due to the limitation of the current instruments and also the rigid structural network of Si3N4

Revival of ferromagnetic behavior in charge-ordered Pr0.75Na0.25MnO3 manganite by ruthenium doping at Mn site and its MR effect

Ru doping in charge-ordered Pr0.75Na0.25Mn1-xRuxO3 (x = 0–0.1) manganites was studied to investigate its effect on structure, electrical transport, magnetic properties, and magnetotransport properties. DC electrical resistivity (ρ), magnetic susceptibility, and χ’ measurements showed that sample x = 0 exhibits insulating behavior within the entire temperature range and antiferromagnetic (AFM) behavior below the charge-ordering (CO) transition temperature TCO of 221 K. Ru4+ substitution (x>0.01) suppressed the CO state, which resulted in the revival of paramagnetic to ferromagnetic (FM) transition at the Curie temperature Tc, increasing from 120 K (x = 0.01) to 193 K (x = 0.1). Deviation from the Curie–Weiss law above Tc in the 1/χ’ versus T plot for x = 0.01 doped samples indicated the existence of Griffiths phase with Griffith temperature at 169 K. Electrical resistivity measurements showed that Ru4+ substitution increased the metallic-to-insulating transition temperature TMI from 144 K (x = 0.01) to 192 K (x = 0.05) due to enhanced double-exchange mechanism, but TMI decreased to 176 K (x = 0.1) probably due to the existence of AFM clusters within the FM domain. The present work also discussed the possible theoretical models at the resistivity curve of Pr0.75Na0.25Mn1-xRuxO3 (x = 0–0.1) for the entire temperature range

Enhancing Photoluminescence Intensity and Spectral Bandwidth of Hybrid Nanofiber/Thin-Film Multilayer Tm3+-Doped SiO2–HfO2

Multilayering of optical thin films is widely used for a range of purposes in photonic technology, but the development of nanofiber structures that can outperform thin films and nanoparticles in optical applications cannot simply be disregarded. Hybrid structures composed of Tm3+-doped SiO2–HfO2 in the form of nanofibers (NFs) and thin films (TFs) are deposited on a single substrate using the electrospinning and dip-coating methods, respectively. Ultrafine nanofiber strands with a diameter of 10–60 nm were fabricated in both single and multilayer samples. Enhanced photoluminescence emission intensity of about 10 times was attained at wavelengths of around 457, 512 and 634 nm under an excitation of 350 nm for NF-TF-NF* hybrid structures when compared with single-layered NF and TF structures. The arrangement of nanofibers and thin films in a multilayer structure influenced the luminescence intensity and spectral bandwidth. High transparency in the range of 75–95% transparency across the wavelength of 200–2000 nm was achieved, making it ideal for photonic application. Theoretical findings obtained through IMD software were compared with experimental results, and they were found to be in good agreement

Ultrafast laser plasma doping of Er3+ ions in silica-on-silicon for optical waveguiding applications

An ultrafast laser plasma doping (ULPD) technique is used for high concentration doping of erbium ions into silica-on-silicon substrate. The method uses a femtosecond laser to ablate material from TeO2-ZnONa2O-Er2O3 (Er-TZN) target glass. The laser generated plasma modifies the silica network, producing high index contrast optical layer suited to the production of on-chip integrated optical circuits. Cross-sectional analysis using scanning electron microscope with energy dispersive xray spectroscopy revealed homogeneous intermixing of the host silica with Er-TZN, which is unique to ULPD. The highly doped layer exhibits spectroscopic characteristics of erbium with photoluminescence lifetimes ranging from 10.79 ms to 14.07 ms

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially