To Access Knowledge Regarding Organ Donation among Healthcare Workers and Their Willingness toward Organ Donation.

BACKGROUND: In India, critical shortage of organ donations, particularly deceased donations, has led to a dire situation in India, with thousands of patients waiting for transplants and a significant number of them succumbing. One of the reasons for the shortage of organs for transplantation is unawareness and prejudiced information about organ donation. Being direct or indirect stakeholders, the knowledge regarding organ donation among healthcare workers may play an important role in the donation process. AIM: To assess the knowledge regarding cadaver organ donation among healthcare workers and their willingness toward organ donation. MATERIALS AND METHODS: It is a cross-sectional offline self-administered questionnaire-based survey conducted among healthcare professionals at tertiary care teaching institutes. Survey was carried out between the months of August to December 2019. A structured questionnaire was used to assess knowledge and willingness toward organ donation. Statistical analyzed was done by using statistical package for social sciences (SPSS) 20.0. All p-values were considered significant at <0.05. RESULTS: A total of 1,039 healthcare professionals participated in the survey. Out of them, 362 (34.8%) were males and 675 (65%) were females. Average age of the healthcare workers participating in survey was 30.81 years, and age ranged from 18 to 60 years. Awareness regarding corneal donation after brain death was found to be maximum (89.7%) and was comparable to that of kidney (86.6%) and heart (83.7%). Participants were unlearned of donation of lungs, pancreas, hands and unaware of heart valve donation. About 45% respondents considered that age affected the donors. About 40% respondents considered younger patients as ideal recipients, while 18.7% respondents considered waiting list patients as ideal recipients. Doctors had highest willingness (78. 3%) for organ donation, followed by nurses (69.9%) and support staff (59.3%) (p < 0.001). Only 119 (11.5%) participants received organ donation cards as against 68.7% willingness toward organ donation (p < 0.01). CONCLUSION: We have observed fair awareness regarding overall cadaver organ donation concept among healthcare workers. There is a need to improve knowledge of extended age criteria and which organs can be retrieved from deceased donor. Authorities have to work hard on delivery of organ donation pledging card to promote donation program.

Identifying Luminescent Boron Vacancies in h-BN Generated Using Controlled He+ Ion Irradiation.

The defect emission from h-BN at 1.55 eV is interesting as it enables optical readout of spins. It is necessary to identify the nature of the relevant point defects for its controlled introduction. However, it is challenging to engineer point defects in h-BN without changing the local atomic structure. Here, we controllably introduce boron vacancies in h-BN using an ultrahigh spatial resolution and low-energy He+ ion beam. By optimizing the He+ ion irradiation conditions, we control the quantity and location of defects spatially and along the depth of h-BN to achieve a robust photoluminescence emission at 1.55 eV from 10 K to room temperature. We show that as-generated defects activate an additional Raman mode at 1295 cm-1. Electron energy loss spectroscopy confirms introduction of boron vacancies without modification of the local h-BN crystal structure. Our results provide a deterministic strategy to create scalable boron vacancy emitters in h-BN for quantum photonics.

Direct Bandgap-like Strong Photoluminescence from Twisted Multilayer MoS2 Grown on SrTiO3.

While direct bandgap monolayer 2D transition metal dichalcogenides (TMDs) have emerged as an important optoelectronic material due to strong light-matter interactions, their multilayer counterparts exhibit an indirect bandgap resulting in poor photon emission quantum yield. We report strong direct bandgap-like photoluminescence at ∼1.9 eV from multilayer MoS2 grown on SrTiO3, whose intensity is significantly higher than that observed in multilayer MoS2/SiO2. Using high-resolution electron microscopy we observe interlayer twist and >8% increase in the van der Waals gap, which leads to weaker interlayer coupling. This affects the evolution of the band structure in multilayer MoS2 as probed by transient absorption spectroscopy, causing higher photo carrier recombination at the direct gap. Our results provide a platform that could enable multilayer TMDs for robust optical device applications.

Evidence of Rotational Fröhlich Coupling in Polaronic Trions.

Electrons commonly couple through Fröhlich interactions with longitudinal optical phonons to form polarons. However, trions possess a finite angular momentum and should therefore couple instead to rotational optical phonons. This creates a polaronic trion whose binding energy is determined by the crystallographic orientation of the lattice. Here, we demonstrate theoretically within the Fröhlich approach and experimentally by photoluminescence emission that the bare trion binding energy (20 meV) is significantly enhanced by the phonons at the interface between the two-dimensional semiconductor MoS_{2} and the bulk transition metal oxide SrTiO_{3}. The low-temperature binding energy changes from 60 meV in [001]-oriented substrates to 90 meV for [111] orientation, as a result of the counterintuitive interplay between the rotational axis of the MoS_{2} trion and that of the SrTiO_{3} phonon mode.

Polaronic Trions at the MoS2 /SrTiO3 Interface.

The reduced electrical screening in 2D materials provides an ideal platform for realization of exotic quasiparticles, that are robust and whose functionalities can be exploited for future electronic, optoelectronic, and valleytronic applications. Recent examples include an interlayer exciton, where an electron from one layer binds with a hole from another, and a Holstein polaron, formed by an electron dressed by a sea of phonons. Here, a new quasiparticle is reported, "polaronic trion" in a heterostructure of MoS2 /SrTiO3 (STO). This emerges as the Fröhlich bound state of the trion in the atomically thin monolayer of MoS2 and the very unique low energy soft phonon mode (≤7 meV, which is temperature and field tunable) in the quantum paraelectric substrate STO, arising below its structural antiferrodistortive (AFD) phase transition temperature. This dressing of the trion with soft phonons manifests in an anomalous temperature dependence of photoluminescence emission leading to a huge enhancement of the trion binding energy (≈70 meV). The soft phonons in STO are sensitive to electric field, which enables field control of the interfacial trion-phonon coupling and resultant polaronic trion binding energy. Polaronic trions could provide a platform to realize quasiparticle-based tunable optoelectronic applications driven by many body effects.

Magneto-Optical Study of Defect Induced Sharp Photoluminescence in LaAlO3 and SrTiO3.

Strongly correlated electronic systems such as Transition Metal Oxides often possess various mid-gap states originating from intrinsic defects in these materials. In this paper, we investigate an extremely sharp Photoluminescence (PL) transition originating from such defect states in two widely used perovskites, LaAlO3 and SrTiO3. A detailed study of the PL as a function of temperature and magnetic field has been conducted to understand the behavior and origin of the transition involved. The temperature dependence of the PL peak position for SrTiO3 is observed to be opposite to that in LaAlO3. Our results reveal the presence of a spin/orbital character in these transitions which is evident from the splitting of these defect energy levels under a high magnetic field. These PL transitions have the potential for enabling non-contact thermal and field sensors.

Origin of Photocarrier Losses in Iron Pyrite (FeS2) Nanocubes.

Iron pyrite has received significant attention due to its high optical absorption. However, the loss of open circuit voltage (Voc) prevents its further application in photovoltaics. Herein, we have studied the photophysics of pyrite by ultrafast laser spectroscopy to understand fundamental limitation of low Voc by quantifying photocarrier losses in high quality, stoichiometric, and phase pure {100} faceted pyrite nanocubes. We found that fast carrier localization of photoexcited carriers to indirect band edge and shallow trap states is responsible for major carrier loss. Slow relaxation component reflects high density of defects within the band gap which is consistent with the observed Mott-variable range hopping (VRH) conduction from transport measurements. Magnetic measurements strikingly show the magnetic ordering associated with phase inhomogeneity, such as FeS2-δ (0 ≤ δ ≤ 1). This implies that improvement of iron pyrite solar cell performance lies in mitigating the intrinsic defects (such as sulfur vacancies) by blocking the fast carrier localization process. Photocarrier generation and relaxation model is presented by comprehensive analysis. Our results provide insight into possible defects that induce midgap states and facilitate rapid carrier relaxation before collection.

Black Phosphorus Transistors with Near Band Edge Contact Schottky Barrier.

Black phosphorus (BP) is a new class of 2D material which holds promise for next generation transistor applications owing to its intrinsically superior carrier mobility properties. Among other issues, achieving good ohmic contacts with low source-drain parasitic resistance in BP field-effect transistors (FET) remains a challenge. For the first time, we report a new contact technology that employs the use of high work function nickel (Ni) and thermal anneal to produce a metal alloy that effectively reduces the contact Schottky barrier height (ΦB) in a BP FET. When annealed at 300 °C, the Ni electrode was found to react with the underlying BP crystal and resulted in the formation of nickel-phosphide (Ni2P) alloy. This serves to de-pin the metal Fermi level close to the valence band edge and realizes a record low hole ΦB of merely ~12 meV. The ΦB at the valence band has also been shown to be thickness-dependent, wherein increasing BP multi-layers results in a smaller ΦB due to bandgap energy shrinkage. The integration of hafnium-dioxide high-k gate dielectric additionally enables a significantly improved subthreshold swing (SS ~ 200 mV/dec), surpassing previously reported BP FETs with conventional SiO2 gate dielectric (SS > 1 V/dec).

Tuning the interface conductivity of LaAlO3/SrTiO3 using ion beams: implications for patterning.

Patterning of the two-dimensional electron gas formed at the interface of two band insulators such as LaAlO3/SrTiO3 is one of the key challenges in oxide electronics. The use of energetic ion beam exposure for engineering the interface conductivity has been investigated. We found that this method can be utilized to manipulate the conductivity at the LaAlO3/SrTiO3 interface by carrier localization, arising from the defects created by the ion beam exposure, eventually producing an insulating ground state. This process of ion-beam-induced defect creation results in structural changes in SrTiO3 as revealed by the appearance of first-order polar TO2 and TO4 vibrational modes which are associated with Ti-O bonds in the Raman spectra of the irradiated samples. Furthermore, significant observation drawn from the magnetotransport measurements is that the irradiated (unirradiated) samples showed a negative (positive) magnetoresistance along with simultaneous emergence of first-order (only second order) Raman modes. In spectroscopic ellipsometry measurements, the optical conductivity features of the irradiated interface are broadened because of the localization effects, along with a decrease of spectral weight from 4.2 to 5.4 eV. These experiments allow us to conclude that the interface ground state (metallic/insulating) at the LaAlO3/SrTiO3 can be controlled by tailoring the defect structure of the SrTiO3 with ion beam exposure. A resist-free, single-step direct patterning of a conducting LaAlO3/SrTiO3 interface has been demonstrated. Patterns with a spatial resolution of 5 µm have been fabricated using a stencil mask, while nanometer scale patterns may be possible with direct focused ion beam writing.