It represents a viable solution for the realization of a portable biosensor platform that could screen/diagnose acute
myocardial infarction by measuring cardiac marker concentrations such as cardiac troponin I (cTnI), creatine kinase MB
(CK-MB), and myoglobin (MYO) for application to u-health monitoring system. The portable biosensor platform
introduced in this presentation has a more compact structure and a much higher measuring resolution than a conventional
spectrometer system. Portable guided-mode resonance (GMR) biosensor platform was composed of a biosensor chip
stage, an optical pick-up module, and a data display panel. Disposable plastic GMR biosensor chips with nano-grating
patterns were fabricated by injection–molding. Whole blood filtration and label-free immunoassay were performed on
these single chips, automatically. Optical pick-up module was fabricated by using the miniaturized bulk optics and the
interconnecting optical fibers and a tunable VCSEL (vertical cavity surface emitting laser). The reflectance spectrum
from the GMR biosensor was measured by the optical pick-up module. Cardiac markers in human serum with
concentrations less than 0.1ng/mL were analyzed using a GMR biosensor. Analysis time was 30min, which is short
enough to meet clinical requirements. Our results show that the GMR biosensor will be very useful in developing lowcost
portable biosensors that can screen for cardiac diseases.
An electrically driven light emission from silicon is a long-standing problem in silicon photonics. Recently, significant progress has been made using silicon quantum dots embedded in silicon nitride thin films, transparent doping layers and electrodes, and surface modified structures. This paper provides an overview of progress in the device physics and fabrications of the nanocrystal silicon light emitting diodes including new device structures to improve the light extraction efficiency as well as highlights in growth of silicon quantum dots and their quantum confinement effects.
The effect of N2O plasma treatment on the reverse leakage currents of InGaN/GaN multiple-quantum well (MQW) light-emitting diodes (LEDs) was investigated. The reverse leakage current of MQW LED chip treated with an N2O plasma was decreased by about 3 orders of magnitude at low reverse voltages compared to that of untreated sample. This could be attributed to the passivation of surface and sidewall damages that were produced by the dry etching process to obtain a reliable pattern transfer. These results suggest that the nonradiative leakage current MQW LED chip can be greatly reduced by N2O plasma passivation, resulting in an improvement in the performance and reliability of MQW LED chip.
InGaN-based light-emitting diode with a micro-roughened top surface using the metal clusters as wet etch masks was investigated. The forward voltage, VF, at 20 mA for InGaN/GaN MQW LED chip with a mirco-roughened top surface was improved compared to that of the conventional InGaN/MQW LED chip. This result could be attributed to the improved metal contact on p-GaN due to an increased contact area between the metal and p-GaN layer. Furthermore, the light-output power for InGaN/GaN MQW LED with micro-roughened top p-GaN surface was increased compared to that for the conventional InGaN/GaN MQW LED chip. This indicate that the scattering of photons emitted in the MQW active layer was much enhanced at the micro-roughened top p-GaN surface of LED due to the angular randomization of photons inside the LED structureu, resulting in an increase in the probability of escaping from the LED structure.
InGaN/GaN multiple-quantum well (MQW) light-emitting diode (LED) was fabricated using a SiO2 current blocking layer (CBL) inserted underneath the p-pad electrode. The forward voltage, Vf at 20 mA for InGaN/GaN MQW LED with a CBL(VF=3.5 V) was slightly higher than that of the conventional InGaN/GaN MQW LED(VF=3.4V) due to the reduction in the total area of p-type metal contact between the transparent Pt layer and the p-GaN. However, the light- output power for InGaN/GaN MQW LED with a CBL at 20 mA was significantly increased by 62% compared to that for the conventional InGaN/GaN MQW LED structure. This increase in the light-output power can be attributed to the more amount of current injected into the active area of the LED through the light-transmitting metal layer and a reduced parasitic optical absorption in the p-pad electrode.
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