A Schottky-Type Metal-Semiconductor-Metal Al0.24Ga0.76N UV Sensor Prepared by Using Selective Annealing.

Asymmetric metal-semiconductor-metal (MSM) aluminum gallium nitride (AlGaN) UV sensors with 24% Al were fabricated using a selective annealing technique that dramatically reduced the dark current density and improved the ohmic behavior and performance compared to a non-annealed sensor. Its dark current density at a bias of -2.0 V and UV-to-visible rejection ratio (UVRR) at a bias of -7.0 V were 8.5 × 10-10 A/cm2 and 672, respectively, which are significant improvements over a non-annealed sensor with a dark current density of 1.3 × 10-7 A/cm2 and UVRR of 84, respectively. The results of a transmission electron microscopy analysis demonstrate that the annealing process caused interdiffusion between the metal layers; the contact behavior between Ti/Al/Ni/Au and AlGaN changed from rectifying to ohmic behavior. The findings from an X-ray photoelectron spectroscopy analysis revealed that the O 1s binding energy peak intensity associated with Ga oxide, which causes current leakage from the AlGaN surface, decreased from around 846 to 598 counts/s after selective annealing.

Correlation of fundus autofluorescence with foveal microstructures and vision in branch retinal vein occlusion.

PURPOSE: To investigate the correlation of fundus autofluorescence (FAF) with the findings of spectral domain optical coherence tomography and visual acuity in patients with branch retinal vein occlusion and to determine the visual prognostic factors. METHODS: Retrospectively, an evaluation of FAF, spectral domain optical coherence tomography images, and visual acuity before and after intravitreal injection of bevacizumab (pre- and post-IVB) was obtained in 42 patients with branch retinal vein occlusion who underwent IVB as their first treatment. The FAF of fovea was graded on a scale of 1 to 4. RESULTS: The visual acuity post-IVB was associated with the visual acuity pre-IVB. Preservation of external limiting membrane and photoreceptor inner and outer segment junction pre- and post-IVB were associated with better visual acuity post-IVB. Eyes with less FAF pre-IVB were closely associated with better visual acuity post-IVB. CONCLUSION: The shorter length of photoreceptor inner and outer segment junction and external limiting membrane defect and less FAF pre-IVB showed a significant association with better visual acuity post-IVB. These associations could help to predict potential restoration of photoreceptor integrity and visual recovery in patients with branch retinal vein occlusion, in whom photoreceptor integrity before treatment could not be adequately evaluated, even with spectral domain optical coherence tomography.

Bridging Implicit and Explicit Geometric Transformation for Single-Image View Synthesis.

Creating novel views from a single image has achieved tremendous strides with advanced autoregressive models, as unseen regions have to be inferred from the visible scene contents. Although recent methods generate high-quality novel views, synthesizing with only one explicit or implicit 3D geometry has a trade-off between two objectives that we call the "seesaw" problem: 1) preserving reprojected contents and 2) completing realistic out-of-view regions. Also, autoregressive models require a considerable computational cost. In this paper, we propose a single-image view synthesis framework for mitigating the seesaw problem while utilizing an efficient non-autoregressive model. Motivated by the characteristics that explicit methods well preserve reprojected pixels and implicit methods complete realistic out-of-view regions, we introduce a loss function to complement two renderers. Our loss function promotes that explicit features improve the reprojected area of implicit features and implicit features improve the out-of-view area of explicit features. With the proposed architecture and loss function, we can alleviate the seesaw problem, outperforming autoregressive-based state-of-the-art methods and generating an image ≈ 100 times faster. We validate the efficiency and effectiveness of our method with experiments on RealEstate10 K and ACID datasets.

Interface Trap Effect on the n-Channel GaN Schottky Barrier-Metal-Oxide Semiconductor Field-Effect Transistor for Ultraviolet Optoelectronic Integration.

Ultraviolet (UV) photodetectors are key devices required in the industrial, military, space, environmental, and biological fields. The Schottky barrier (SB)-MOSFET, with its high hole and electron barrier, and given its extremely low dark current, has broad development prospects in the optoelectronics field. We analyze the effects of trap states on the output characteristics of an inversion mode n-channel GaN SB-MOSFET using TCAD simulations. At the oxide/GaN interface below the gate, it was demonstrated that shallow donor-like traps were responsible for degrading the subthreshold swing (SS) and off-state current density (Ioff), while deep donor-like traps below the Fermi energy level were insignificant. In addition, shallow acceptor-like traps shifted the threshold voltage (Vt) positively and deteriorated the SS and on-state current density (Ion), while deep acceptor-like traps acted on a fixed charge. The output characteristics of the GaN SB-MOSFET were related to the resistive GaN path and the tunneling rate due to the traps at the metal (source, drain)/GaN interface. For the UV responses, the main mechanism for the negative Vt shift and the increases in the Ion and spectral responsivity was related to the photo-gating effect caused by light-generated holes trapped in the shallow trap states. These results will provide insights for UV detection technology and for a high-performance monolithic integration of the GaN SB-MOSFET.

Correlation of fundus autofluorescence with spectral-domain optical coherence tomography and vision in diabetic macular edema.

PURPOSE: To investigate the correlation between fundus autofluorescence (FAF) and the results of spectral-domain optical coherence tomography (SD-OCT) as well as visual acuity (VA) in patients with diabetic macular edema (DME) and to determine the visual prognostic factors. DESIGN: Retrospective, interventional case series. PARTICIPANTS: Sixty-one patients with DME who underwent intravitreal injection of bevacizumab (IVB) as their first treatment. METHODS: An assessment of VA and FAF and SD-OCT images were obtained before and after IVB (pre- and post-IVB). Foveal FAF was graded on a scale of 1 to 4. The presence or absence of FAF at the foveola was also determined. MAIN OUTCOME MEASURES: The association of FAF with VA and the SD-OCT results, including central macular thickness (CMT), outer nuclear layer thickness, the integrity of the external limiting membrane (ELM), and the integrity of the junction between the inner and outer segment of the photoreceptor (IS/OS). RESULTS: Better VA, preservation of the ELM, and IS/OS pre-IVB were associated with better VA post-IVB. Of the types of DME, cystoid macular edema significantly correlated with increased FAF at the foveola. A higher level of FAF was 5.6 times more likely to occur in DME with a defect in IS/OS and 10 times more likely to occur with each 10-µm increase in CMT. Each increase by a factor of 0.1 in the logarithm of the minimum angle of resolution (logMAR) pre-IVB increased the probability of high FAF by a factor of 1.73. Despite severe DME, fewer eyes with a low level of FAF exhibited an IS/OS defect and large logMAR VA than eyes with a high level of FAF with severe DME pre-IVB. The average grade of FAF pre-IVB was higher in patients with decreased vision during follow-up than in patients with increased or unchanged good vision. CONCLUSIONS: The strong association of FAF with SD-OCT parameters and VA in patients with DME could aid in the prediction of the restoration of photoreceptor integrity and subsequent visual recovery, especially in patients with severe DME, in whom photoreceptor integrity before treatment could not be adequately evaluated, even with SD-OCT.

Comparison of risk factors for initial central scotoma versus initial peripheral scotoma in normal-tension glaucoma.

PURPOSE: To investigate the risk factors for initial central scotoma (ICS) compared with initial peripheral scotoma (IPS) in normal-tension glaucoma (NTG). METHODS: Fifty-six NTG patients (56 eyes) with an ICS and 103 NTG patients (103 eyes) with an IPS were included. Retrospectively, the differences were assessed between the two groups for baseline characteristics, ocular factors, systemic factors, and lifestyle factors. Also, the mean deviation of visual field was compared between the two groups. RESULTS: Patients from both ICS and IPS groups were of similar age, gender, family history of glaucoma, and follow-up periods. Frequency of disc hemorrhage was significantly higher among patients with ICS than in patients with IPS. Moreover, systemic risk factors such as hypotension, migraine, Raynaud's phenomenon, and snoring were more prevalent in the ICS group than in the IPS group. There were no statistical differences in lifestyle risk factors such as smoking or body mass index. Pattern standard deviation was significantly greater in the ICS group than in the IPS group, but the mean deviation was similar between the two groups. CONCLUSIONS: NTG Patients with ICS and IPS have different profiles of risk factors and clinical characteristics. This suggests that the pattern of initial visual field loss may be useful to identify patients at higher risk of central field loss.