Keithley 4200A-SCS Reference Manual page 1155

Appendix D: Using a Model 82 C-V System
Equilibrium test (QTsweep) description
This test performs a quasistatic capacitance measurement (CQS) using 20 different delay times. The
voltage bias and pulse amplitude are held constant during the test. The current (Q / t) at the end of
each reading sample is also calculated (i = ∆Q/∆t).
The figure below shows the pulse stream for the equilibrium test using the parameters shown in
QTsweep (equilibrium test)
(Delay_Max) of one second, while the first reading sample uses a delay of 70 ms (which is the
minimum). The delay times for the other 18 reading samples are then automatically set. After the first
pulse, each subsequent pulse delay time increases logarithmically in progression up to the maximum
delay (Delay_Max).
The generated graph for this test plots:
•
Quasistatic capacitance (CQS) vs. delay time
•
Leakage current (Q / t) vs. delay time
A typical graph for the equilibrium test is shown here. The optimal delay time occurs when both
curves flatten out to a slope of zero. For maximum accuracy, choose the second point on the curves
after they have flattened out.
D-14
Model 4200A-SCS Parameter Analyzer Reference Manual
(on page D-12). As shown, the last reading sample uses a set delay
Figure 591: Equilibrium test
Figure 592: Equilibrium test graph
4200A-901-01 Rev. C / February 2017