I have a Bottom Gate TFT transistor: 

* W/l=320um
* Substrate: corning glass
* Gate: 60nm Molibdenum
* Dielectric: 350 nm Ta2O5 
* Semiconductor: 30nm IGZO 
* S-D: Molibdenum 60nm

It is wired like so (if anyone knows the circuit symbol for TFT i'll edit it): 

[![Circuit][1]][1]

I am forcing pulses of Current IDS and registering VGS
This is what it looks like on the SMU:

* PLot 1: CH1 IDS VS time
* Plot 2: Ch1 VGS vs time
 
[![Plots][2]][2]

I want to wire a second transistor in the same way, get a recording VGS2 and then find the difference VGS1-VGS2.

## The application
I am using the TFT to detect Ionizing radiation: The X-ray radiation creates electron-hole pairs in the Dielectric, which then affect the VGS recorded for a fixed ISD

Here is a plot showing how the VGS curve changes with the radiation exposure 
[![VGS vs Time][3]][3]


  [1]: https://i.sstatic.net/Z0MZv.png
  [2]: https://i.sstatic.net/lpcKn.png
  [3]: https://i.sstatic.net/9GFJ5.png