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8 NanoTech
8.10 CNT Vth gmMax: CNT FET linear region Vth (A.01.20)
[Supported Analyzer]
B1500A, 4155B, 4155C, 4156B, 4156C
[Description]
Extracts the threshold voltage (Vth) from linear region data by using the extrapolation method for the
measurement of CNT FET Id-Vg characteristics.
[Device Under Test]
Carbon Nano Tube FET, 4 terminals
[Device Parameters]
Polarity: Forward (SMUs force the specified value) or Reverse (SMUs force the negative specified value)
L: CNT length
D: CNT diameter
Temp: Temperature
IdMax: Drain current compliance
[Test Parameters]
IntegTime: Integration time
BackGate: SMU connected to Back Gate, primary sweep voltage output
VbgStart: Sweep start voltage for Back Gate
VbgStop: Sweep stop voltage for Back Gate
VbgStep: Sweep step voltage for Back Gate
Drain: SMU connected to Drain, constant voltage output
Vd: Drain voltage, ideally at around 100mV
SideGate: SMU connected to Side Gate, constant voltage output
Source: SMU connected to Source, constant voltage output
[Extended Test Parameters]
Vsg: Side Gate voltage
Vs: Source voltage
IbgLimit: Back Gate current compliance
HoldTime: Hold time
DelayTime: Delay time
gm_Min: Minimum transconductance value for Y axis
gm_Max: Maximum transconductance value for Y axis
DrainMinRng: Minimum range for drain current measurement
[Measurement Parameters]
Drain current Idrain
[User Function]
gm=diff(Idrain,Vbackgate)
[Analysis Function]
gmMax=max(gm)
Von=@L1X (X intercept of Line1)
Vth=Von-Vd/2
Vth is given by the following formula.
Vth=Vg(gmMax)-Id(gmMax)/gmMax
Vd/2 is for compensation of the secondary term of Vd in the theoretical formula.
Agilent EasyEXPERT Application Library Reference, Edition 8
8-15