For GaN compound semiconductors, the position of dislocations was confirmed by STEM, and the elemental distribution was clarified by APT. From the results of APT, cluster segregation of Mg and In was ...observed on the dislocation, and it could be considered that they were diffused along the dislocations.
This paper presents an ultra-low power batteryless energy harvesting body sensor node (BSN) SoC fabricated in a commercial 130 nm CMOS technology capable of acquiring, processing, and transmitting ...electrocardiogram (ECG), electromyogram (EMG), and electroencephalogram (EEG) data. This SoC utilizes recent advances in energy harvesting, dynamic power management, low voltage boost circuits, bio-signal front-ends, subthreshold processing, and RF transmitter circuit topologies. The SoC is designed so the integration and interaction of circuit blocks accomplish an integrated, flexible, and reconfigurable wireless BSN SoC capable of autonomous power management and operation from harvested power, thus prolonging the node lifetime indefinitely. The chip performs ECG heart rate extraction and atrial fibrillation detection while only consuming 19 Formula OmittedW, running solely on harvested energy. This chip is the first wireless BSN powered solely from a thermoelectric harvester and/or RF power and has lower power, lower minimum supply voltage (30 mV), and more complete system integration than previously reported wireless BSN SoCs.
The field of organic electronics thrives on the hope of enabling low‐cost, solution‐processed electronic devices with mechanical, optoelectronic, and chemical properties not available from inorganic ...semiconductors. A key to the success of these aspirations is the ability to controllably dope organic semiconductors with high spatial resolution. Here, recent progress in molecular doping of organic semiconductors is summarized, with an emphasis on solution‐processed p‐type doped polymeric semiconductors. Highlighted topics include how solution‐processing techniques can control the distribution, diffusion, and density of dopants within the organic semiconductor, and, in turn, affect the electronic properties of the material. Research in these areas has recently intensified, thanks to advances in chemical synthesis, improved understanding of charged states in organic materials, and a focus on relating fabrication techniques to morphology. Significant disorder in these systems, along with complex interactions between doping and film morphology, is often responsible for charge trapping and low doping efficiency. However, the strong coupling between doping, solubility, and morphology can be harnessed to control crystallinity, create doping gradients, and pattern polymers. These breakthroughs suggest a role for molecular doping not only in device function but also in fabrication—applications beyond those directly analogous to inorganic doping.
Strong interactions between molecular dopants and organic semiconductor morphology are often responsible for charge trapping and low doping efficiency. This study reviews how solution‐processing techniques can control these interactions and render them useful for engineering diffusion rates, doping gradients, and film topography. These breakthroughs suggest new roles for molecular doping in device fabrication as well as function.
We report a successful application of atomic layer deposition (ALD) aluminum oxide as a passivation layer to gallium nitride high electron-mobility transistors (HEMTs). This new passivation process ...results in 8%-10% higher dc maximum drain current and maximum extrinsic transconductance, about one order of magnitude lower drain current in the sub-threshold region, 10%-20% higher pulsed-Formula Omitted drain current, and 27%-30% higher RF power with simultaneously 5-8 percentage point higher power-added efficiency. The achieved improvement in device performance is attributed to the outstanding quality of the interface between III-N and the ALD aluminum oxide resulting from the uniqueness of the adopted ALD process, featuring a wet-chemical-based wafer preparation as well as a pregrowth self-cleaning procedure in the growth chamber. This technology can be readily integrated into the HEMT-based integrated circuit fabrication process, making the ALD aluminum oxide-passivated GaN HEMTs excellent candidates for multiple microwave and millimeter-wave power applications.
A novel program-inhibit phenomenon of "negative" cell Formula Omitted shift has been investigated for the first time in Formula Omitted self-aligned shallow trench isolation nand Flash memory cells. ...The negative Formula Omitted shift is caused in an inhibit cell when along-word-line adjacent cell is programming. The magnitude of the negative shift becomes larger in the case of higher program voltage Formula Omitted, lower field oxide height, slower program speed of the adjacent cell, and high Formula Omitted of victim cell. The experimental results suggest that the mechanism of negative Formula Omitted shift is attributed to hot holes that are generated by FN electron injection from channel/junction to the control gate. This phenomenon will become worse with cell size scaling since hot hole generation is increased by increasing the electron injection due to narrower floating gate space. Therefore, this negative Formula Omitted shift phenomenon is one of the new scaling limiters of nand Flash memory cell, which needs to be managed for 2 and 3 b/cell in Formula Omitted nm and beyond nand Flash memories.
High-performance gas sensors prepared using p-type oxide semiconductors such as NiO, CuO, Cr2O3, Co3O4, and Mn3O4 were reviewed. The ionized adsorption of oxygen on p-type oxide semiconductors leads ...to the formation of hole-accumulation layers (HALs), and conduction occurs mainly along the near-surface HAL. Thus, the chemoresistive variations of undoped p-type oxide semiconductors are lower than those induced at the electron-depletion layers of n-type oxide semiconductors. However, highly sensitive and selective p-type oxide-semiconductor-based gas sensors can be designed either by controlling the carrier concentration through aliovalent doping or by promoting the sensing reaction of a specific gas through doping/loading the sensor material with oxide or noble metal catalysts. The junction between p- and n-type oxide semiconductors fabricated with different contact configurations can provide new strategies for designing gas sensors. p-Type oxide semiconductors with distinctive surface reactivity and oxygen adsorption are also advantageous for enhancing gas selectivity, decreasing the humidity dependence of sensor signals to negligible levels, and improving recovery speed. Accordingly, p-type oxide semiconductors are excellent materials not only for fabricating highly sensitive and selective gas sensors but also valuable additives that provide new functionality in gas sensors, which will enable the development of high-performance gas sensors.
An All-Silicon Passive Optical Diode Fan, Li; Wang, Jian; Varghese, Leo T. ...
Science (American Association for the Advancement of Science),
01/2012, Letnik:
335, Številka:
6067
Journal Article
Recenzirano
Odprti dostop
A passive optical diode effect would be useful for on-chip optical information processing but has been difficult to achieve. Using a method based on optical nonlinearity, we demonstrate a ...forward-backward transmission ratio of up to 28 decibels within telecommunication wavelengths. Our device, which uses two silicon rings 5 micrometers in radius, is passive yet maintains optical nonreciprocity for a broad range of input power levels, and it performs equally well even if the backward input power is higher than the forward input. The silicon optical diode is ultracompact and is compatible with current complementary metal-oxide semiconductor processing.
We present a 2-Kb one-time programmable (OTP) memory for UHF RFID applications. The OTP memory cell is based on a two-transistor (2-T) gate-oxide anti-fuse (AF) for low voltage operation. Reliability ...of memory cell is enhanced by limiting the maximum terminal voltages of thin-oxide and thick-oxide transistors to 1.8 V and 3.3 V, respectively. Improved low power circuit design techniques are used including auto shut-off for program mode and self-timed control for read mode. To further reduce power consumption, we develop a novel power-efficient charge pump. The designed OTP is successfully embedded into a UHF passive RFID tag IC that conforms to the EPCglobal Gen-2 standard. The tag chip was fabricated in a 0.18 Formula Omitted 1-poly 6-metal standard CMOS process with no additional masks. The total area of the chip including the I/Os and bonding pads is Formula Omitted where the OTP memory area is only Formula Omitted. Our tag IC measurement shows that the read and write currents of the OTP memory are 17 Formula Omitted and 58 Formula Omitted, respectively.
Delivering milliwatts of wireless power at centimeter distances is advantageous to many existing and emerging biomedical applications. It is highly desirable to fully integrate the receiver on a ...single chip in standard CMOS with no additional post-processing steps or external components. This paper presents a 2Formula Omitted2.18 Formula Omitted on-chip wireless power transfer (WPT) receiver (Rx) coil fabricated in 0.13 Formula Omitted CMOS. The WPT system utilizes a 14.5Formula Omitted 14.5 Formula Omitted transmitter (Tx) coil that is fabricated on a standard FR4 substrate. The on-chip power harvester demonstrates a peak WPT efficiency of Formula Omitted, Formula Omitted and Formula Omitted at 10 mm of separation through air, bovine muscle and 0.2 molar NaCl, respectively. The achieved efficiency enables the delivery of milliwatts of power to application circuits while staying below safe power density and electromagnetic (EM) exposure limits.
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