I am measuring a photoresponse of graphene devices using lock in preamplifier SR830. I would like to analyse the photoresponse dependence on back gate bias. As an easy solution, I've used computer controlled Keithley 2636B. However, whenever the bias is changed on Keithley it makes massive spikes in the signal detected by lock in. I've tried varying the chopping frequency, no result. I am quite confused, since I am not sure why this is happening. I've contacted Keithley, but unfortunately they were not helpful. I've contacted Stanford research but never got their reply. The set up configuration is as following: source/drain of the photodetector are connected as A and B for the lock in to provide A-B measurement, the drain and back gate are connected to the Keithley. It should be noted that drain has both lock in preamp and Keithley connected, this contact is also put on the ground.
Hello Viktoryia,
With the information you provided about your experiment is difficult to help you finding the source of the behavior you observe.
The Lock-in amplifier is connected to a photodetector while the voltage source is connected to the device right?.
If this is the case, is the light you are trying to detect with the lock-in being generated by the graphene device? or you have a light source inciding onto the gpraphene device as well?
Hi Jose,
Thanks a lot for your interest in my problem, I've updated my question including the information on the set up. Please let me know whether this helps. Thanks!
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