The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical ...The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical excitation.By inspecting the I-V curves under optical and electrical excitation at identical injection current,it has been found that the I-V curves exhibit apparent differences in voltage values.Furthermore,the differences are found to originate from the junction temperatures in diverse excitation ways.Experimental results indicate that if the thermal effect of illuminating spot is depressed to an ignorable extent by using pulsed light,the junction temperature will hardly deflect from that under optical excitation,and then the I-V characteristics under two diverse excitation ways will be the same.展开更多
A new electrical resistance tomography (ERT) system, based on the bi-directional current pulse technique, is de- veloped. Polarization effects at the electrodes are eliminated. During each half cycle of the excitation...A new electrical resistance tomography (ERT) system, based on the bi-directional current pulse technique, is de- veloped. Polarization effects at the electrodes are eliminated. During each half cycle of the excitation process, direct current (DC) is used as the excitation source and filtering is not needed. Moreover, using optimized data collection protocol, the number of current injections for a 16-electrode system is reduced to 14 for 104 independent readings of an image. Experimental results showed that the system is effective using the sensitivity coefficient algorithm for image reconstruction.展开更多
In this work, we present an experimental transient 3-Dimensionnal study for the minority charge carriers’ effective lifetime measurement under magnetic field in transient dynamic state. The magnitude of the magnetic ...In this work, we present an experimental transient 3-Dimensionnal study for the minority charge carriers’ effective lifetime measurement under magnetic field in transient dynamic state. The magnitude of the magnetic field B is varied from 0 mT to 0.03 mT. The method used is mainly based on the open circuit voltage decay method. The solar cell is injected by a low electrical excitation which protects against capacitance effects. Our approach is based on the open circuit voltage decay response analysis. From an experimental set-up, we get the transient voltage data on a digital scope. The data are used for plotting transient voltage decay curves. The curves obtained and analyzed are fitted in their linear zone. This zone presents an ideal decay which permits to get good values of lifetime. The slope of the linear decay is inversely proportional to effective lifetime. The results of fitting permit determinate the effective charge carriers’ lifetime directly. The results obtained are then presented and analyzed. The observations indicate that the charge carriers effective lifetime decrease when the magnetic field increases.展开更多
基金Project supported by the National Natural Science Foundation of China(No.61006053)the National Science Foundation ofCQ CSTC (No.CSTC 2008BB3156)
文摘The factors influencing the current-voltage（I-V） characteristics of light-emitting diodes（LEDs） are investigated to reveal the connection of I-V characteristics under optical excitation and those under electrical excitation.By inspecting the I-V curves under optical and electrical excitation at identical injection current,it has been found that the I-V curves exhibit apparent differences in voltage values.Furthermore,the differences are found to originate from the junction temperatures in diverse excitation ways.Experimental results indicate that if the thermal effect of illuminating spot is depressed to an ignorable extent by using pulsed light,the junction temperature will hardly deflect from that under optical excitation,and then the I-V characteristics under two diverse excitation ways will be the same.
基金Project (No. 2001BA701A46) supported by the Hi-Tech Researchand Development Program (863) of China
文摘A new electrical resistance tomography (ERT) system, based on the bi-directional current pulse technique, is de- veloped. Polarization effects at the electrodes are eliminated. During each half cycle of the excitation process, direct current (DC) is used as the excitation source and filtering is not needed. Moreover, using optimized data collection protocol, the number of current injections for a 16-electrode system is reduced to 14 for 104 independent readings of an image. Experimental results showed that the system is effective using the sensitivity coefficient algorithm for image reconstruction.
文摘In this work, we present an experimental transient 3-Dimensionnal study for the minority charge carriers’ effective lifetime measurement under magnetic field in transient dynamic state. The magnitude of the magnetic field B is varied from 0 mT to 0.03 mT. The method used is mainly based on the open circuit voltage decay method. The solar cell is injected by a low electrical excitation which protects against capacitance effects. Our approach is based on the open circuit voltage decay response analysis. From an experimental set-up, we get the transient voltage data on a digital scope. The data are used for plotting transient voltage decay curves. The curves obtained and analyzed are fitted in their linear zone. This zone presents an ideal decay which permits to get good values of lifetime. The slope of the linear decay is inversely proportional to effective lifetime. The results of fitting permit determinate the effective charge carriers’ lifetime directly. The results obtained are then presented and analyzed. The observations indicate that the charge carriers effective lifetime decrease when the magnetic field increases.
