I tested the photodetection performance of Se nanowires. When I measure Current as a funtion of Time with a fixed bias I am observing that under UV light illumination the current increseas with respect to dark current. But while doing I-V under the illumination of varying intensity of UV light the photocurrent decreased as compared to dark current. Could someone please help me to understand why is it so?
Hi, Thripuranthaka!
It is not clear from your description of the role played by TIME. What kind of characteristics you describe - static or dynamic? It would be better if the two curves have been shown graphically with the indication axis and parameters.
Best regards!
For me, it is not also clear the description of your experiment. I have a short experience with the characterization of single ZnO nanowire based photoconductors, and I would like to tell you some suggestions that you probably already know.
1. You should measure first the dark current level of your nanowire. Remember that the nanowire has a nanometric cross-section, then the current density through a nanowire is extremely high even using low voltages. Therefore, you should not use extremely high voltages. In this regard, you can prevent nanowire heating and degradation overtime.
2. Secondly, you could measure the rise and decay time of your nanowire by illuminating the nanowire with UV light.
3. Finally, you can measure the light current under UV illumination.
In my opinion, the only way possible to observe a dark current level higher than the light current in a photoconductor, is because of the dark current was not measured properly, i.e. it was measured after illumination when the "intrinsic" dark level has not been reached.
Regards
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