We fabricated two Photoconductor type MoS2 based Photodetector device. In one we noticed Positive photoresponse and Negative photoresponse on the other. How to define and explain these two phenomena in terms of carrier movement or any other mechanism. Basically I would appreciate if anyone could explain the correct definition of positive and negative photoresponse in photodetector devices.
TIA.
I think that photons are absorbed in photoresists. The energy of photons can degrade bounds in a type of photoresist while those can give their energy to electrons for binding in another type.
Hello,
What kind of photodetectors are you talking about ?
In the case of a PiN diode, the negative responsivity is explained by the fact that more electrons are collected directly at the p-contact.
I observed negative photoresponse in the VUV range due to the photoemission (cf paper below, figure 2).
Article Radiometric characteristics of new diamond PIN photodiodes
What will be the explanation of negative photoresponse if one is using Schottky contact based photodiode? @Ali Ben
under reverse bias, right ?
in this context, and under photons illumination, it seems that more electrons are flowing from SC to metal contact (which should be negligible in principle due to the increase of the barrier).
You need to double-check if you have indeed a barrier (schottky contact ?).
Dear Mohammad Soroosh sir, We did not use any photo-resist materials, first we used drop and cast method to have the materials on the substrates and later we used FIB to fabricate contacts. Despite this fact, how will you define the nature of photo-response ?
Ali BenMoussa In our case, we fabricated a non-conventional photo-conductor type photodetector device where we used MoS2 (N-Type SC) and another materials (Insulator in nature), active in NIR region, which makes the device a NI type device (does it make sense?). The MoS2 base is the, upon changing the insulating materials we are getting two different types of photo-response, +ive, and -ive. Mohamed Yousef Hassan Yes! we have used same illumination intensity. I am looking for a clear definition of these two phenomena. Please put forward your best knowledge.
Thanks a lot.
Your device make sense indeed (kind of inverted PIN). But it could help to have also a schematic representation (geometry) of the detector.
Do you use MoS2 also has contact or do you have an ohmic contact for the MoS2 side ? what is the (multilayer) metal contact used in the insulator side ? Any thermal treatment added ?
A
what is wavelength and intesnvity of light? iam sending link, it may helpful you
http://iopscience.iop.org/article/10.1088/1361-6528/aaded6/pdf
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