We investigated the optical and electrical properties of red AlGaInP light-emitting diodes (LEDs) as functions of chip size, p-cladding layer thickness, and the number of multi-quantum wells (MQWs). External quantum efficiency (EQE) decreased with decreasing chip size. The ideality factor gradually increased from 1.47 to 1.95 as the chip size decreased from 350 μm to 15 μm. This indicates that the smaller LEDs experienced larger carrier loss due to Shockley-Read-Hall nonradiative recombination at sidewall defects. S parameter, defined as ∂lnL/∂lnI, increased with decreasing chip size. Simulations and experimental results showed that smaller LEDs with 5 pairs of MQWs had over 30% higher IQE at 5 A/cm than the LED with 20 pairs of MQWs. These results show that the optimization of the number of QWs is needed to obtain maximum EQE of micro-LEDs.
The method of a unilateral extrapedicular approach in kyphoplasty and vertebroplasty in the lumbar area might be similar to that in thoracic approach using a route via the extrapedicular space. However, different anatomical characteristics of the lumbar area should be considered.
Half of patients had inappropriate laminar profiles to accommodate a 3.5 mm screw in at least one side of the axis. The three-dimensional computed tomography reconstruction is mandatory for the preoperative assessment for the feasibility of the C2 lamina.
In this paper, we investigated an anomalous hump in the bottom gate staggered amorphous indium-gallium zinc oxide thin-film transistors. During the positive gate bias stress, a positive threshold voltage shift is observed in transfer curve and an anomalous hump occurs as the stress time increases. The hump becomes more serious as the gate bias stress increases while it is not observed under the negative bias stress. From the simulation of a long range migration of zinc interstitial ions (Zni) and the measurement of the diode characteristics after the constant positive bias stress, the origin of the hump can be explained by the migration of the positively charged mobile Zni during the constant positive gate bias stress, which can be conformed by increasing the concentration of Zni from the result of the Auger ZnL3M4.5M4.5 spectra.
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