i have another problem about the graphene/ni interface.i made the Van der pauw type sample and characterize it using Hall Effect measurements but i get the lowest mobility value of 80 cm2/(V·s). can u ask me the reason and the nickel interface effect on graphene properties and mobility. i am sharing a little bit result
Thickness(m) = 1.230000E-9
Dimensions(mm^2) = 10.0 X 10.0
Temperature (K) : 3.00E+2
I(A) = 1.000000E-2
B Field(G) = 5300.000
Rs(ohm/sq) = 1.951028E-1
Rho(ohm-cm) = 2.399764E-8
Con(1/ohm-cm) = 4.167076E+7
VH(V) = -7.879118E-6
RH(m^3/C) = -1.828550E-12
Sample Type = N
Ns(/cm^2) = -4.198457E+17
N(/cm^3) = -3.413379E+24
Mobility(cm^2/Vs) = 7.619708E+1
can any one till me why the mobility is low
Dear Shah,
Can you specify what type of graphene are you using? I'm assuming it is CVD graphene grown on nickle.
The sheet resistance value and the sheet carrier density are too good to be true for practically obtained graphene in general and CVD graphene which generally exhibits large amount of grain boundaries and defects.
I believe that the current measured during your explained setup is passing through the nickle film underneath, which is why you are getting such good values.
A realistic sheet resistance for pristine CVD graphene would range from few hundreds to a thousands ohm/sq.
I would recommend you to repeat the measurement by placing the graphene on an insulating substrate (Glass)
dear Ahmed you r right its CVD.actually i am measuring the interface effects of ni on graphene in terms of electrical properties
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