Showing papers by "Peng Zhou published in 2016"

Tunable Ambipolar Polarization-Sensitive Photodetectors Based on High-Anisotropy ReSe2 Nanosheets.

Abstract: Atomically thin 2D-layered transition-metal dichalcogenides have been studied extensively in recent years because of their intriguing physical properties and promising applications in nanoelectronic devices. Among them, ReSe2 is an emerging material that exhibits a stable distorted 1T phase and strong in-plane anisotropy due to its reduced crystal symmetry. Here, the anisotropic nature of ReSe2 is revealed by Raman spectroscopy under linearly polarized excitations in which different vibration modes exhibit pronounced periodic variations in intensity. Utilizing high-quality ReSe2 nanosheets, top-gate ReSe2 field-effect transistors were built that show an excellent on/off current ratio exceeding 107 and a well-developed current saturation in the current–voltage characteristics at room temperature. Importantly, the successful synthesis of ReSe2 directly onto hexagonal boron nitride substrates has effectively improved the electron motility over 500 times and the hole mobility over 100 times at low temperature...

Elevated Transforming Growth Factor-β2 in the Aqueous Humor: A Possible Explanation for High Rate of Capsular Contraction Syndrome in High Myopia.

Abstract: Purpose. The purpose of the study was to elucidate the role of transforming growth factor-beta 2 (TGF-β2) in the development of high myopic capsular contraction syndrome. Methods. Nineteen cases of capsular contraction syndrome, including 14 with high myopia, were collected, and their clinical data were reviewed. Aqueous humor and anterior capsular membranes were obtained during capsulotomy. Hematoxylin-eosin and immunohistochemical staining with anti-TGF-β2 antibody were performed on capsular membranes. TGF-β2 levels in aqueous humor were assayed using ELISA and western blot. Results. High myopia was significantly associated with the incidence of capsular contraction syndrome (odds ratio: 14.74, P < 0.001, 95% CI: 5.29-41.05). Histopathological analysis revealed proliferation of fibroblast-like lens epithelial cells on the shrunken anterior capsule, labeled with TGF-β2 antibodies. ELISA and Western blot showed higher levels of TGF-β2 in aqueous humor of patients with capsular contraction syndrome and high myopia. Conclusions. High myopia is a risk factor for capsular contraction syndrome. Elevated TGF-β2 levels in high myopic cataract patients may play an important role in the pathogenesis of capsular contraction syndrome.

Controlling the work function of molybdenum disulfide by in situ metal deposition.

Abstract: Control of the work function of molybdenum disulfide (MoS2) under ultrathin metal was investigated using in situ metal deposition and direct ultraviolet photoelectron spectroscopy measurement in an ultra-high vacuum system. When the metal thickness turned from two dimensional into bulk, the work function was also raised up at the nickel-MoS2 interface, barely changed at the titanium-MoS2 interface and lowered at the hafnium-MoS2 interface. Meanwhile, the mechanisms of charge transfer and band alignment with metal deposition were also discussed. The Schottky barrier at metal-MoS2 interfaces could be tailored by both types and thicknesses of deposited metal. The low work function metal was a good indicator for MoS2 contact electrodes. It paved the way towards future high performance MoS2 device applications.

Comparison between Limbal and Pars Plana Approaches Using Microincision Vitrectomy for Removal of Congenital Cataracts with Primary Intraocular Lens Implantation

Abstract: Purpose. To compare the surgical outcomes of limbal versus pars plana vitrectomy using the 23-gauge microincision system for removal of congenital cataracts with primary intraocular lens implantation. Methods. We retrospectively reviewed all eyes that underwent cataract removal through limbal or pars plana incision. Main outcome measures included visual outcomes and complications. Results. We included 40 eyes (26 patients) in the limbal group and 41 eyes (30 patients) in the pars plana group. The mean age was 46 months. There was no significant difference in best-corrected visual acuity between the two groups (P = 0.64). Significantly, more eyes had at least one intraoperative complication in the limbal group than in the pars plana group (P = 0.03) that were mainly distributed at 1.5-3 years of age (P = 0.01). The most common intraoperative complications were iris aspiration, iris prolapse, and iris injury. More eyes in the limbal group had postoperative complications and required additional intraocular surgery, but the difference was not significant (P = 0.19). Conclusions. The visual results were encouraging in both approaches. We recommend the pars plana approach for lower incidence of complications. The limbal approach should be reserved for children older than 3 years of age and caution should be exercised to minimize iris disturbance.

Study on electrical defects level in single layer two-dimensional Ta2O5 *

Abstract: Two-dimensional atomic-layered material is a recent research focus, and single layer Ta2O5 used as gate dielectric in field-effect transistors is obtained via assemblies of Ta2O5 nanosheets. However, the electrical performance is seriously affected by electronic defects existing in Ta2O5. Therefore, spectroscopic ellipsometry is used to calculate the transition energies and corresponding probabilities for two different charged oxygen vacancies, whose existence is revealed by x-ray photoelectron spectroscopy analysis. Spectroscopic ellipsometry fitting also calculates the thickness of single layer Ta2O5, exhibiting good agreement with atomic force microscopy measurement. Nondestructive and noncontact spectroscopic ellipsometry is appropriate for detecting the electrical defects level of single layer Ta2O5.

Mobility enhancement and hysteresis phenomenon in WSe 2 FETs

Abstract: Two-dimensional materials are layered materials with outstanding electrical and optical properties in atomic thickness. Here we report on a back-gate transistor with a two-dimensional material WSe 2 as channel material. Our device shows a significant mobility enhancement by Atomic layer deposition (ALD), from ∼0.95 cm2/Vs to ∼26 cm2/Vs. Moreover, we explored the hysteresis phenomenon in our device and fitted our data to make the mechanism clear.