We have observed charge trapping during constant voltage stress in Hf-based high-dielectrics at deep traps as well as at the shallow traps. ⌬V FB and leakage current dependence on these deep traps further suggest that trapping at deep levels inhibits fast ⌬V T recovery. The earlier findings where charge trapping seemed to be very transient due to the presence of a large number of shallow traps and trapped charge could be eliminated by applying a reverse direction electric field may no longer be valid. The experimentally observed trap energy levels from low-temperature measurements establish a relationship between the origin of the deep traps and their dependence on O vacancy formation in Hf-silicate-based films. Substrate hot electron injection gives rise to significant electron trapping and slow post-stress recovery under negative bias conditions, which confirms that O-vacancy-induced deep defects determine the transient behavior in Hf-silicate-based high-gate dielectrics. It is further shown that negative-U transition to deep defects is responsible for trap-assisted tunneling under substrate injection. A fraction of the injected electrons remains trapped at the deep defects and gives rise to significant ⌬V FB . This has the potential to be the ultimate limiting factor for the long-term reliability of Hf-based high-gate dielectrics.Transistor scaling has so far achieved remarkable success in optimizing the diverse objectives like operational speed and lower power consumption. However, further downscaling of metal oxide semiconductor field effect transistor ͑MOSFET͒ sizes, specifically oxide thickness ͑t ox ͒ below 1.6 nm, increases transistor leakage current to levels unacceptable for low-power applications. 1 An attractive solution is to replace SiO 2 with high-dielectric materials ͑mostly Hf-, Zr-, and Al-based͒ while retaining the standard MOSFET design. Stringent application of the physical and electrical criteria like permittivity, band structure offset, thermodynamic stability, interface quality, gate-electrode compatibility, process compatibility, reliability, etc., shows Hf-based oxides as the most potential candidates out of many alternatives available. 2 In particular, Hf-silicates and their nitrided alloys are more likely to be the first generation of implementable high-. They have a moderately high dielectric constant ͑ϳ8 to 15͒, depending on Hf content. But, it is compensated by higher thermal stability, better leakage characteristics, improved threshold instability, and lower mobility degradation compared to HfO 2 . 3,4 In addition, silicates form better interfaces than metal oxides. However, long-term reliability remains the most critical factor to hold back its successful incorporation into the mainstream commercial integrated circuits ͑ICs͒.For high-gate stacks, trapping within bulk dielectric is widely reported to be the most critical reliability issue. 1,2,5,6 First, significant hysteresis due to very fast charging and discharging of the trapped carriers causes transient threshold voltage inst...

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Integrating microfluidics with biosensors is of great research interest with the increasing trend of lab-on-the chip and point-of-care devices. Though there have been numerous studies performed relating microfluidics to the biosensing mechanisms, the study of the sensitivity variation due to microfluidic flow is very much limited. In this paper, the sensitivity of interdigitated electrodes was evaluated at the static drop condition and the microfluidic flow condition. In addition, this study demonstrates the use of gold nanoparticles to enhance the sensor signal response and provides experimental results of the capacitance difference during cancer antigen-125 (CA-125) antigen–antibody conjugation at multiple concentrations of CA-125 antigens. The experimental results also provide evidence of disease-specific detection of CA-125 antigen at multiple concentrations with the increase in capacitive signal response proportional to the concentration of the CA-125 antigens. The capacitive signal response of antigen–antibody conjugation on interdigitate electrodes has been enhanced by approximately 2.8 times (from 260.80 to 736.33 pF at 20 kHz frequency) in static drop condition and approximately 2.5 times (from 205.85 to 518.48 pF at 20 kHz frequency) in microfluidic flow condition with gold nanoparticle-coating. The capacitive signal response is observed to decrease at microfluidic flow condition at both plain interdigitated electrodes (from 260.80 to 205.85 pF at 20 kHz frequency) and gold nano particle coated interdigitated electrodes (from 736.33 to 518.48 pF at 20 kHz frequency), due to the strong shear effect compared to static drop condition. However, the microfluidic channel in the biosensor has the potential to increase the signal to noise ratio due to plasma separation from the whole blood and lead to the increase concentration of the biomarkers in the blood volume for sensing.

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The authors report on the achievement of full-color nanowire light-emitting diodes (LEDs), with the incorporation of InGaN/AlGaN nanowire heterostructures grown directly on the Si (111) substrates by molecular beam epitaxy. Multiple color emission across nearly the entire visible wavelength range can be realized by varying the In composition in the InGaN quantum dot active region. Moreover, multiple AlGaN shell layers are spontaneously formed during the growth of InGaN/AlGaN quantum dots, leading to the drastically reduced nonradiative surface recombination, and enhanced carrier injection efficiency. Such core–shell nanowire structures exhibit significantly increased carrier lifetime and massively enhanced photoluminescence intensity compared to conventional InGaN/GaN nanowire LEDs. A high color rendering index of ∼98 was recorded for white-light emitted from such phosphor-free core–shell nanowire LEDs.