The low-temperature relaxation processes in TlGa.sub.1 - .sub.xDy.sub.xSe.sub.2 (x = 0.01, 0.03) single crystals have been studied experimentally. The physical parameters which characterize the ...electron processes in Ag-TlGa.sub.1 - .sub.xDy.sub.xSe.sub.2-Ag samples have been determined using the estafette transfer mechanism of the charge formed at deep traps due to the carrier injection from a contact: the effective mobility of the charge transferred due to deep centers, the sample contact capacity, the region of accumulation of the charge in the samples, the contact charging constant, and the flight time of charge carriers through the sample.
Polarization is a common and unique phenomenon in nature, which reveals more camouflage features of objects. However, current polarization-perceptual devices based on conventional physical ...architectures face enormous challenges for high-performance computation due to the traditional von Neumann bottleneck. In this work, a novel polarization-perceptual neuro-transistor with reconfigurable anisotropic vision is proposed based on a two-dimensional ReS
phototransistor. The device exhibits excellent photodetection ability and superior polarization sensitivity due to its direct band gap semiconductor property and strong anisotropic crystal structure, respectively. The fascinating polarization-sensitive neuromorphic behavior, such as polarization memory consolidation and reconfigurable visual imaging, are successfully realized. In particular, the regulated polarization responsivity and dichroic ratio are successfully emulated through our artificial compound eyes. More importantly, two intriguing polarization-perceptual applications for polarized navigation with reconfigurable adaptive learning abilities and three-dimensional visual polarization imaging are also experimentally demonstrated. The proposed device may provide a promising opportunity for future polarization perception systems in intelligent humanoid robots and autonomous vehicles.
Hydrogen plays a crucial role in several oxide semiconductors, where the amount of hydrogen significantly influences the device performance. Thus, its manipulation in oxide semiconductors is ...important for device performance. In our investigation, we studied the effect of hydrogen on defects in In-G-Zn-O semiconductor thin-film transistors (TFTs), as it varies with Al2O3 atomic layer deposition temperature. We found that the total trap-density (Formula Omitted) extracted by the sub-threshold slope and the trap density (Formula Omitted) measured by low-frequency noise (LFN) as well as the density-of-states analyzed by capacitance-voltage decreased with increasing amounts of hydrogen in the oxide semiconductor. Given that LFN data show that mobility fluctuation is the major origins of noise and the front channel of TFT is a major carrier transport region, our results indicate that hydrogen effectively passivates the defects in front channel of oxide semiconductor and contributes to achieving superior device performance.
Compared with bulk-Si wafer, Al x Ga1- x N/gallium nitride (GaN) heterostructures grown on a 150-mm silicon-on-insulator (SOI) substrate with a 35-nm-thick Si overlayer are shown to have Formula ...Omitted% less wafer bowing. As a result, the 2-D electron gas mobility and the sheet-resistivity uniformity on SOI are improved due to a lower defect density. In terms of device performance, high-electron-mobility transistors (HEMTs) fabricated on the Al x Ga1- x N/GaN-on-SOI exhibit Formula Omitted% higher saturation drain current as compared with the bulk-Si counterparts. However, due to the poorer conductivity of the buried oxide layer, the Al x Ga1- x N/GaN-on-SOI HEMT suffers greater self-heating, with Formula Omitted K higher channel temperature. With mitigation of self-heating, the Al x Ga1- x N/GaN-on-SOI, in view of its more superior structural and thermal stability, should offer an attractive alternative for integration of the GaN technology with the Si CMOS platform.
An unprecedented catalytic system composed of the Wilkinson catalyst Rh(PPh3)3Cl and CF3COOH enabled the highly regioselective cross-coupling of aromatic amines with a variety of heteroarenes ...through dual CH bond cleavage. This protocol provided a facile and rapid route from readily available substrates to (2-aminophenyl)heteroaryl compounds, which may be conveniently transformed into highly extended π-conjugated heteroacenes. The experimental studies and calculations showed that thianaphtheno3,2-bindoles have large HOMO-LUMO energy gaps and low-lying HOMO levels, and could therefore potentially be high-performance organic semiconductors. Herein we report the first use of a rhodium(I) catalyst for oxidative CH/CH coupling reactions. The current innovative catalyst system is much less expensive than RhCp*Cl22/AgSbF6 and could open the door for the application of this approach to other types of CH activation processes.
Synthesis and characterization of π-conjugated homo- and co-oligomers based on thiophene substituted in position 3 by pentyl (3PT) and naphthylvinyl (NVT) side groups are presented. The resultant ...co-oligomers have statistical structure and the proportion of monomers can be fully controlled by the composition of the reaction mixture. The approach here offers a facile way to synthesis of materials with tunable optoelectrical properties that is an alternative for complicated organometallic synthesis involving water and oxygen sensitive Sn, Pd, or Mg compounds. The UV-vis absorption and fluorescence emission spectra depend on and can be easily tuned by the 3PT:NVT monomer molar ratio. Combination of these two monomers has a strong synergistic effect on the color of the fluorescence emission that varies in a broad range, from orange to blue color. X-ray diffraction, calorimetric, and materials display electrical properties characteristic for organic semiconductors.
A new method for the synthesis of highly substituted naphthyridine-based polyheteroaromatic compounds in high yields proceeds through rhodium(III)-catalyzed multiple CH bond cleavage and CC and CN ...bond formation in a one-pot process. Such highly substituted polyheteroaromatic compounds have attracted much attention because of their unique π-conjugation, which make them suitable materials for organic semiconductors and luminescent materials. Furthermore, a possible mechanism, which involves multiple chelation-assisted ortho CH activation, alkyne insertion, and reductive elimination, is proposed for this transformation.
Small-molecule organic semiconductors have displayed remarkable electronic properties with a multitude of π-conjugated structures developed and fine-tuned over recent years to afford highly efficient ...hole- and electron-transporting materials. Already making a significant impact on organic electronic applications including organic field-effect transistors and solar cells, this class of materials is also now naturally being considered for the emerging field of organic bioelectronics. In efforts aimed at identifying and developing (semi)conducting materials for bioelectronic applications, particular attention has been placed on materials displaying mixed ionic and electronic conduction to interface efficiently with the inherently ionic biological world. Such mixed conductors are conveniently evaluated using an organic electrochemical transistor, which further presents itself as an ideal bioelectronic device for transducing biological signals into electrical signals. Here, we review recent literature relevant for the design of small-molecule mixed ionic and electronic conductors. We assess important classes of p- and n-type small-molecule semiconductors, consider structural modifications relevant for mixed conduction and for specific interactions with ionic species, and discuss the outlook of small-molecule semiconductors in the context of organic bioelectronics.
In this brief, a 14-bit 500 MS/s current-steering digital-to-analog converter (DAC) is proposed, which applies the novel grouped random rotation thermometer code (GRTC) and the differential-quad ...switching (DQS) and has good dynamic performance without calibrations. The GRTC suppresses the harmonics caused by element mismatches, while the DQS reduces the input-code transition-dependent distortion to achieve a high spurious-free dynamic range (SFDR). A unit current cell with an intrinsic precision of 12 bits rather than 14 bits is used to reduce the active area, and the simple diagonal structure with a common-centroid layout is adopted to reduce the gradient error. The measured SFDR of the proposed DAC is more than 80 dBc below 35 MHz and better than 68 dBc over the entire Nyquist bandwidth. The power consumption of the DAC core is only 67.7 mW at 500 MS/s. The proposed DAC has been implemented in the Semiconductor Manufacturing International Corporation (SMIC) 0.18-Formula Omittedm CMOS process and occupies an active area of only 0.55 Formula Omitted.
