Do you get correct graph of transfer characteristic, if you take +ive Vds(constant) value instead of -ive. As mostly CNTFETs are p-chnl FET

I’m studying transfer characteristic curve of CNTFET to get value for mobility, S.S, etc. According to my basic background knowledge, NMOS curves lie in the 1st quadrant. While for PMOS they lie in the 3rd quadrant. As mostly CNTFETs are p-channel, I was expecting mine one to lie in the 3rd quadrant (-ive Id current, -ive Vgs). But in my case, the curve lies in 2nd quadrant, current is positive, due to which slope comes out to be negative(calculated it for mobility).

I think I’ve made a mistake. While taking Vgs Vs Ids(graph attached), Vds is constant. I just took positive values of Vds. for example for the given graph(attached) constant Vds is 0.1V. Now I’ve come to know that one has to take -ive constant value for Vds when calculating Transfer characteristic for p-channel mosfet.

Questions:

Are my all reading wrong?

what should I do? I can’t perform the experiment again. Kindly help is there any way for my readings to be correct? If they are already correct then any explanation for this behavior?

I even connected my MOSFET for both kinds of biasing (for n channel and for p channel), that’s because CNTs I’ve used are mixed(semiconducting plus metallic). So I thought I might get good results for n-channel one. For p-channel, the curve was in the 3rd quadrant while for n channel biasing it was in 4th. So not in the one it should be(1st,3rd). Keithley source meter was used to obtain IV-curves. kindly help, I hope you are getting my point and sorry for typing mistakes as my electronics is not that good enough.