Investigation of Thermal Stress Degradation in Indium-Gallium-Zinc-Oxide TFTs

The performance of IGZO TFTs has improved significantly in recent years, however device stability still remains a significant issue. Thermal stability of IGZO TFTs be- comes very crucial to ensure desired performance of end-product. Both bottom-gate (BG) and double-gate (DG) TFTs were observed to degrade with hotplate treatments under 200◦C. Such events are rarely reported in the literature, and thus became the primary focus of this work. The mechanism causing the instability is not completely understood, however experimental results indicate the instability occurs either di- rectly or indirectly due to the influence of H2O within the passivation oxide above the IGZO channel region. DG TFTs saw more pronounced degradation, which led to the hypothesis that there may be a reaction of the top gate metal with H2O molecules in the passivation oxide, liberating monatomic hydrogen. Both H2O and hydrogen behave as donor states in IGZO, thus rendering the channel more conduc- tive. The thermal stability also demonstrated a dependence on channel length, with shorter channel devices showing greater stability. This may be due to the metalized source/drain regions acting as effective getter to water during a 400◦C passivation anneal which is performed prior to top-gate metal deposition. This hypothesis led to an investigation on atomic layer deposition (ALD) of capping layers over the passiva- tion oxide of IGZO TFTs to act as an effective barrier to water/hydrogen migrating to the underlying IGZO channel

Tuning Bandgap and Energy Stability of Organic-Inorganic Halide Perovskites through Surface Engineering

Organohalide perovskite with a variety of surface structures and morphologies have shown promising potential owing to the choice of the type of heterostructure dependent stability. We systematically investigate and discuss the impact of 2-dimensional molybdenum-disulphide (MoS2), molybdenum-diselenide (MoSe2), tungsten-disulphide (WS2), tungsten-diselenide (WSe2), boron- nitiride (BN) and graphene monolayers on band-gap and energy stability of organic-inorganic halide perovskites. We found that MAPbI3ML deposited on BN-ML shows room temperature stability (-25 meV~300K) with an optimal bandgap of ~1.6 eV. The calculated absorption coefficient also lies in the visible-light range with a maximum of 4.9 x 104 cm-1 achieved at 2.8 eV photon energy. On the basis of our calculations, we suggest that the encapsulation of an organic-inorganic halide perovskite monolayers by semiconducting monolayers potentially provides greater flexibility for tuning the energy stability and the bandgap.Comment: 19 pages (single sided), 5 figures, 1 Tabl

Tuning Bandgap and Energy Stability of Organic-Inorganic Halide Perovskites through Surface Engineering

Organohalide perovskite with a variety of surface structures and morphologies have shown promising potential owing to the choice of the type of heterostructure dependent stability. We systematically investigate and discuss the impact of 2-dimensional molybdenum-disulphide (MoS2), molybdenum-diselenide (MoSe2), tungsten-disulphide (WS2), tungsten-diselenide (WSe2), boron- nitiride (BN) and graphene monolayers on band-gap and energy stability of organic-inorganic halide perovskites. We found that MAPbI3ML deposited on BN-ML shows room temperature stability (-25 meV~300K) with an optimal bandgap of ~1.6 eV. The calculated absorption coefficient also lies in the visible-light range with a maximum of 4.9 x 104 cm-1 achieved at 2.8 eV photon energy. On the basis of our calculations, we suggest that the encapsulation of an organic-inorganic halide perovskite monolayers by semiconducting monolayers potentially provides greater flexibility for tuning the energy stability and the bandgap.Comment: 19 pages (single sided), 5 figures, 1 Tabl

A prospective observational study on adverse drug reactions of iohexol contrast media in computed tomography imaging studies

Background: Iohexol is widely used radiocontrast media in the radiology departments for the diagnostic imaging purpose. As very few studies are carried out focusing on safety profiles of this contrast media. This study was conducted to know the profile of adverse drug reactions (ADRs) induced by Iohexol in patients who are undergoing the contrast-enhanced computed tomography (CECT) examination.Methods: Total 106 patients from CT unit of radiology department were observed for adverse drug reactions from Iohexol contrast media in 2 months duration. Acute ADRs were recorded immediately after contrast media administration by observation and personal interviews and delayed ADRs are recorded by follow up after 24hrs.Results: Total 23 out of 106 patients who had undergone CT imaging investigations by Iohexol contrast media had developed ADRs. Total 29 ADRs were developed in 23 patients. Out of these, 22 ADRs were acute and 7 ADRs were delayed reactions. All acute ADRs were of “probable” category and all delayed ADRs were of “possible” category according to WHO-UMC and Naranjo’s causality assessment scales. All ADRs were at Level-1 according to Modified Hartwig and Siegel severity scale. Preventability assessment of ADRs using Modified Schumock and Thornton preventability scale showed that all the ADRs were of “not preventable” class. All 29 ADRs were of TYPE U (Unclassified) as per the Wills and Brown method.Conclusions: All reactions are physiologic and are mild in nature. No life-threatening reactions are observed during the entire study period. Development of ADRs in female patients seen higher than male patients. So, this population requires a special attention for any serious contrast media reactions

Tuning phase-stability and short-range order through Al-doping in (CoCrFeMn)100-xAlx high entropy alloys

For (CoCrFeMn)$_{100-x}$Al$_{x}$ high-entropy alloys, we investigate the phase evolution with increasing Al-content (0 $\le$ x $\le$ 20 at.%). From first-principles theory, the Al-doping drives the alloy structurally from FCC to BCC separated by a narrow two-phase region (FCC+BCC), which is well supported by our experiments. We highlight the effect of Al-doping on the formation enthalpy and electronic structure of (CoCrFeMn)$_{100-x}$Al$_{x}$ alloys. As chemical short-range order (SRO) in multicomponent alloys indicates the nascent local order (and entropy changes), as well as expected low-temperature ordering behavior, we use thermodynamic linear-response within density-functional theory to predict SRO and ordering transformation and temperatures inherent in (CoCrFeMn)$_{100-x}$Al$_{x}$. The predictions agree with our present experimental findings, and other reported ones.Comment: 27 pages, 9 figures, 1 tabl

Incremental cycle bases for cycle-based pose graph optimization

Pose graph optimization is a special case of the simultaneous localization and mapping problem where the only variables to be estimated are pose variables and the only measurements are inter-pose constraints. The vast majority of PGO techniques are vertex based (variables are robot poses), but recent work has parameterized the pose graph optimization problem in a relative fashion (variables are the transformations between poses) that utilizes a minimum cycle basis to maximize the sparsity of the problem. We explore the construction of a cycle basis in an incremental manner while maximizing the sparsity. We validate an algorithm that constructs a sparse cycle basis incrementally and compare its performance with a minimum cycle basis. Additionally, we present an algorithm to approximate the minimum cycle basis of two graphs that are sparsely connected as is common in multi-agent scenarios. Lastly, the relative parameterization of pose graph optimization has been limited to using rigid body transforms on SE(2) or SE(3) as the constraints between poses. We introduce a methodology to allow for the use of lower-degree-of-freedom measurements in the relative pose graph optimization problem. We provide extensive validation of our algorithms on standard benchmarks, simulated datasets, and custom hardware