Agilent Technologies EasyEXPERT, Manual, Page: 379 / 610

12 Sample
12.1 Vth gmMax and Id: Extrapolation Vth and Constant Vth (A.04.00)
[Supported Analyzer]
B1500A, 4155B, 4155C, 4156B, 4156C
[Description]
Measures MOSFET Id-Vg characteristics, and extracts the threshold voltage (Vth) by the extrapolation
method and the threshold voltage (Vth@Id) by the constant current method.
[Device Under Test]
MOSFET, 4 terminals
[Device Parameters]
Polarity: Nch (SMUs force the specified value) or Pch (SMUs force the negative specified value).
Lg: Gate length
Wg: Gate width
Temp: Temperature
IdMax: Drain current compliance
[Test Parameters]
IntegTime: Integration time
Id@Vth: Drain current to decide Vth by the constant current method
Gate: SMU connected to Gate terminal, primary sweep voltage output
VgStart: Sweep start voltage for Gate terminal
VgStop: Sweep stop voltage for Gate terminal
VgStep: Sweep step voltage for Gate terminal
Drain: SMU connected to Drain terminal, constant voltage output
Vd: Drain voltage
Subs: SMU connected to Substrate, constant voltage output
Vsubs: Substrate voltage
Source: SMU connected to Source terminal, constant voltage output
[Extended Test Parameters]
Vs: Source voltage
IgLimit: Gate current compliance
IsubsLimit: Substrate current compliance
HoldTime: Hold time
DelayTime: Delay time
DrainMinRng: Minimum range for the drain current measurement
[Measurement Parameters]
Drain current Idrain
[User Function]
gm=diff(Idrain,Vgate)
[Analysis Function]
gmMax=max(gm)
Von=@L1X (X intercept of Line1)
Vth=Von-Vd/2
Vth@Id=@MX (X coordinate of Marker)
Vth is given by the following formula.
Vth=Vg(gmMax)-Id(gmMax)/gmMax
Agilent EasyEXPERT Application Library Reference, Edition 8
12-3