I have fabricated an OFET and run the I-V characteristics. I have some problem where my output characteristics shows only linear region and there is no saturation region. What causes the output characteristics operated in linear region and no saturation region. Thanks in advance.
Dear Adilah,
welcome,
would you please display your output I-V curves. Th OFETs are characterized by high voltage ranges. It may then that you restricted the voltage range to the linear region. It may be to enter the saturation region you need to apply much higher VDS. The organic field effect transistor saturates because of the drift velocity saturation in the organic fets.
Best wishes
Please see this paper
Can help you surely
Influence of Molecular Weight on the Short-Channel Effect in Polymer-Based Field-Effect Transistors
January 2012Journal of Polymer Science Part A-2 Polymer Physics
DOI: 10.1002/polb.22353
Dear Prof Abdelhalim Zekry,
Thank you for your reply. Here I attached the image of my output characteristics OFET. Yes, I agreed with you maybe because there is not enough of voltage supply. But there is a limitation in my SMU where I just can ramp up until 40 V. So I have to find reasons and justify why this is happened. I have read somewhere, this might be attributed to the short channel SCLC effects. But, I still could not understand well the mechanism. I really hope you can help.
Thank you, Prof.
Thank you Dr W. Boukhili for you answer and suggestion of paper. I will read and understand the paper. thank you.
Dear A dilah,
welcome again,
By inspecting your i-v curves it is apparent that you have high leakage current at zero VGS pointing out an appreciable conduction. This conduction may be due to a preformed channel or due to to a parasitic conduction path from the source to the drain. If a channel is formed one can check it by applying a positive voltage such that if the conduction is suppressed means that there is a preformed channel. If not means that you there is aparasetic conduction path that must be eliminated by elaborate fabrication of the organic channel material.
The nonlinear behavior of the drain current points out the current conduction is not limited by a drift current but it is limited by space charge limited current flow which is one of the major current conduction at the high electric field in the organic materials because of its low mobility and single type charge injection. Such current is proportional to V^n with n= 2. in a trap free semiconductor and n can take greater values in case of traps. For more information please refer to the link: https://www.researchgate.net/post/How_is_the_current_limited_in_metal_organic_semiconductor_metal_MOSM_diode
Best wishes Adilah
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