Light Dependent Temperature Characteristics of a-Si - H p-i-n Photodiode.

As a result of chemical reactions in certain biological samples, thermal energy can be released that affects the transducer response of optical label-free biosensors used in lab-on-chip applications. To improve and understand the sensitivity limitations, the transient thermal characteristics of the a-Si:H p-i-n photodiode are measured and analyzed. We report the results obtained with the device operating at different reverse bias voltages (200 mV and 1 V) in the dark and under illumination with blue LED. The behavior of the sensor was studied at temperatures ranging from 30 to 55°C. The temperature of the sample was actively stabilized by a feedback loop. The fluctuations of the photodiode current and its time dependence were observed. These results could explain the increased sensitivity of the photodiode in the previous analysis of biological samples.