Gao Yiqing

Far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under forward DC bias

The far-infrared electroluminescence characteristics of an InGaP/InGaAs/Ge solar cell are investigated under forward DC bias at room temperature in dark conditions. An electroluminescence viewgraph shows the clear device structures, and the electroluminescence intensity is shown to increases exponentially with bias voltage and linearly with bias current. The results can be interpreted using an equivalent circuit of a single ideal diode model for triple-junction solar cells. The good fit between the measured and calculated data proves the above conclusions. This work is of guiding significance for current solar cell testing and research.

A Fiber Optic Sensor for Real Time Monitoring of the Curing/cured State of Adhesives

Adhesives are widely used in the assembly of optoelectronic and/or electronic components. Based on the principle of Fresnel reflection, a fiber optic refract meter was set up to monitor the state of adhesives. The determined refractive indices of various liquids were consistent with their reference technical data. When taking a real time monitoring of adhesive refractivity on the refract meter, curing process of the adhesive and thermal expansion of the cured adhesive could be distinguished. Finally, the temperature dependence of the adhesive refractivity was verified with thermo-mechanical analysis through the Lorenz-Lorentz relation. Experimental results show that the setup can be a candidate replacement of thermal analysis apparatus.

Far-infrared electroluminescence characteristics of an Si-based photodiode under a forward DC bias current

At room temperature, the bias dependence of a far-infrared electroluminescence image of a photodiode is investigated in the dark condition. The results show that the electroluminescence image can be used to detect defects in the photodiode. Additionally, it is found that the electroluminescence intensity has a power law dependence on the dc bias current. The photodiode ideality factor could be obtained by a fitting a relationship between the electroluminescence intensity and the bias current. The device defect levels will be easily determined according to the infrared image and the extracted ideality factor value. This work is of guiding significance for current solar cell testing and research.