Tektronix Keithley SourceMeter 2470 User Manual

Model 2470
High Voltage SourceMeter Instrument User's Manual Section 6: Measure I-
V characteristics of FETs
2470-900-01 Rev. B / August 2019 6-17
-- Find actual gate voltage (and indexes) closest to fitHighV and fitLowV
for i = 1, gate.defbuffer1.n do
gateV = gate.defbuffer1.sourcevalues[i]
if math.abs(gateV - fitHighV) < diffHighV then
diffHighV = math.abs(gateV - fitHighV)
gateHighV = gateV
fitHighIndex = i
end
if math.abs(gateV - fitLowV) < diffLowV then
diffLowV = math.abs(gateV - fitLowV)
gateLowV = gateV
fitLowIndex = i
end
end
-- Find drain current and natural log of current at the two fit voltages
local drainHighI = drain.defbuffer1.readings[fitHighIndex]
local drainLowI = drain.defbuffer1.readings[fitLowIndex]
local ln_drainHighI = math.log(drainHighI)
local ln_drainLowI = math.log(drainLowI)
-- Find subthreshold swing, S, inverse of subthreshold slope, multiply by 1000 for mV/dec
local diffgateV = gateHighV - gateLowV
local diff_ln_drainI = ln_drainHighI - ln_drainLowI
local S = (diffgateV / diff_ln_drainI) * 1000
-- Print the results
print(string.format("Subthreshold Swing = %.4f mV/decade", S))
print(string.format("High current in fit = %.6E A, low current in fit = %.6E A",
drainHighI, drainLowI))
print("Index,".."\t".."gateV (V),".."\t".."drainI (A)")
for k = 1, stepPoints do
print(
string.format("%d,\t%.5f,\t%.6E",
k, gate.defbuffer1.sourcevalues[k], drain.defbuffer1.readings[k]
)
)
end
Set up the drain family of curves measurement using TSP
commands
The following TSP code uses the trigger model to generate a drain family of curves on a FET using
two 2470s communicating with each other using TSP-Link. The SMU at Node 1 is connected to the
gate and steps voltage from 2 V to 5 V in four steps. The SMU at Node 2 is connected to the drain
and sweeps voltage from 0 V to 5 V with 51 points at each step.
After the code is executed, the measurement results are displayed in the Instrument Console of Test
Script Builder. From the Instrument Console, you can copy the data into a spreadsheet for graphing.

Tektronix Keithley SourceMeter 2470 Specifications

General

Brand	Tektronix
Model	Keithley SourceMeter 2470
Category	Measuring Instruments
Language	English