Neuropathic pain is a kind of chronic pain that remains difficult to treat due to its complicated underlying mechanisms. Accumulating evidence has indicated that enhanced synaptic plasticity of nociceptive interneurons in the superficial spinal dorsal horn contributes to the development of neuropathic pain. Neuroligin1 (NL1) is a type of excitatory postsynaptic adhesion molecule, which can mediate excitatory synaptic activity, hence promoting neuronal activation. Vglut2 is the most common marker of excitatory glutamatergic neurons. To explore the role of NL1 in excitatory neurons in nociceptive regulation, we used transgenic mice with cre recombinase expression driven by the Vglut2 promoter combined with viral vectors to knockdown the expression of NL1 in excitatory neurons in the spinal dorsal horn. We found that NL1 was upregulated in the L4–L6 spinal dorsal horn in Vglut2-cre +/– mouse subjected to spared nerve injury (SNI). Meanwhile, the expression of phosphorylated cofilin (p-cofilin) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit 1 (GluR1) was also increased. Spinal microinjection of a cre-dependent NL1-targeting RNAi in Vglut2-cre +/– mouse alleviated the neuropathic pain-induced mechanical hypersensitivity and reduced the increase in p-cofilin and GluR1 caused by SNI. Taken together, NL1 in excitatory neurons regulates neuropathic pain by promoting the SNI-dependent increase in p-cofilin and GluR1 in the spinal dorsal horn. Our study provides a better understanding of the role of NL1 in excitatory neurons, which might represent a possible therapeutic target for alleviating neuropathic pain.
A minority carrier lifetime of 25.46 $\mu$s in a P-type 4H-SiC epilayer has been attained through sequential thermal oxidation and hydrogen annealing. Thermal oxidation can enhance the minority carrier lifetime in the 4H-SiC epilayer by reducing carbon vacancies. However, this process also generates carbon clusters with limited diffusivity and contributes to the enlargement of surface pits on the 4H-SiC. High-temperature hydrogen annealing effectively reduces stacking fault and dislocation density. Moreover, electron spin resonance analysis indicates a significant reduction in carbon vacancy defects after hydrogen annealing. The mechanisms of the elimination of carbon vacancies by hydrogen annealing include the decomposition of carbon clusters formed during thermal oxidation and the low-pressure selective etching by hydrogen, which increases the carbon content on the 4H-SiC surface and facilitates carbon diffusion. Consequently, the combination of thermal oxidation and hydrogen annealing eliminates carbon vacancies more effectively, substantially enhancing the minority carrier lifetime in P-type 4H-SiC. This improvement is advantageous for the application of high-voltage SiC bipolar devices.
The electrical properties of Ti/Au contacts to anatase TiO 2 nanocrystal films are investigated under different thermal annealing temperature (300–500 °C) in a N 2 ambient. The as-deposited contact shows a non-linear current–voltage ( I – V ) property. However, after being annealed at 300 °C and 400 °C, the samples exhibit nearly ohmic I – V behaviors with currents at 5 V bias higher than that of as-deposited one by about three and seven times, respectively. When the annealing temperature is increased to 500 °C, the ohmic contact transform to Schottky contact. The influence of annealing temperatures on Ti/Au contacts to anatase TiO 2 nanocrystal films depends on the interdiffusion behavior between the electrode layers and TiO 2 films, which was investigated by Auger electron spectroscopy. Possible mechanisms are proposed to explain the influence of annealing temperature on the electrical properties of Ti/Au contacts to anatase TiO 2 nanocrystal films.
In this report, 4H-SiC p-i-n photodiodes with various micro-hole arrays are fabricated, then measured and discussed by using photoelectric measurement system and simulation software. Periodic micro-hole arrays etched from p layer to i layer are obtained by using the selective etching technology, which increases the photosensitive area of devices and reduces the ultraviolet light absorption of p layer. The average dark current of devices has an ultralow value of approximate $6.0\times 10 ^{-15}$ A in the low reverse bias range of 0–10 V. Furthermore, the device with $4 ~\mu \text{m}$ micro-hole exhibits the best performance and its peak responsivity increased by 10.4 % compared to the conventional device. It is significant that the peak responsivity and corresponding external quantum efficiency of devices with $4 ~\mu \text{m}$ micro-hole at 40 V bias are 815 % and 819 % higher than those of devices without micro-hole, respectively. This is attribute to the fact that a high electric field is observed around the micro-holes as the reverse bias increased to 40 V, which leads to local avalanche. Thus, the local avalanche photodiodes work at a relatively low bias, which improved the responsivity and quantum efficiency of the device enormously.
In this brief, high-performance $8\times8$ arrays of 4H-SiC p-i-n ultraviolet (UV) photodiodes (PDs) with micro-hole structure are demonstrated. In order to improve the performance of the device, a periodic micro-hole structure (diameter = $4~\mu \text{m}$ ) was etched from the cap layer (p + layer) to the i layer, which will elevate the effective absorption of UV light. The pixels in 4H-SiC p-i-n array show a low dark current of less than $2\times 10^{-{14}}$ A and a high yield of 98.4%. Devices with 4- $\mu \text{m}$ micro-hole reach a peak spectral responsivity of 0.159 A/W at 280 nm, which is 23.3% higher than that of the device without micro-hole. Moreover, the device has a faster response time of 2.2 ns and a high UV/visible rejection ratio of more than $10^{{4}}$ . The progress on the response performance is significant to the development of UV detection imaging.
ABSTRACT Hydrogenated amorphous silicon carbide (a-Si1-xCx:H) films were deposited by RF plasma enhanced chemical vapor deposition (PECVD) and subsequently annealed in N2 atmosphere at different temperatures. Systematic investigations of the deposition temperature and annealing effect on the film's properties, including film thicknesses, optical bandgap, refractive indexes, absorption coefficient (α), chemical bond configurations, stoichiometry and crystalline structures, were performed using ellipsometry, FTIR absorbance spectroscopy, Raman spectroscopy, XPS, and XRD. All of the results indicate that the structural and optical properties of the a-Si1-xCx:H film can be effectively engineered by proper annealing conditions. Moreover, molecular vibrational level equation was introduced to explain the peak shift detected by FTIR and Raman spectroscopy.
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