Gamma1 - Keithley S530 User Manual

S530 Parametric Test System Test Subroutine Library User's Manual

gamma1

This subroutine returns the value of the body effect parameter gamma obtained from two measurements of the
threshold voltage (V
T
Usage
double gamma1(int d, int g, int s, int sub, double vlow, double vhigh, double vds,
double vbs1, double vbs2, double phip, double ithr, double vstep, int npts, int
*kflag)
d
g
s
sub
vlow
vhigh
vds
vbs1
vbs2
phip
ithr
vstep
npts
kflag
Returns
Details
This subroutine estimates body effect from V
parameter characterizes the effect of the substrate bias on threshold voltage. The V
using the vtext2 subroutine.
The equation used in this subroutine:
 = V
-V
T2
Where:

 = MOSFET body effect constant

V = Threshold voltage at the first value of V
T1

V = Threshold voltage at the second value of V
T2


= Surface potential (twice the Fermi level)
p
The npts parameter must be greater than 5. If a value less than 5 is used, the subroutine uses 5
points by default.
S530-907-01 Rev. A / September 2015
) at different substrate bias voltages (V
Input The drain pin of the device
Input The gate pin of the device
Input The source pin of the device
Input The substrate pin of the device
Input Low limit of the expected threshold
Input High limit of the expected threshold
Input Drain-source voltage, in volts
First substrate to source voltage
Second substrate to source voltage
Surface potential, in volts
Drain-source trigger current (I
Gate-source voltage (V
The number of points in the sweep
Output Returned status flag:



Output Estimated body effect
/V + -V + )
T1 T1 p T2 p
).
BS
), in amperes
DS
) step size, in volts
GS
0 = Normal completion
1 = First V measurement failed
T
2 = second V measurement failed
T
measured at two V
T
BS
BS
Section 3: Test subroutine library reference
values. The body effect
BS
data is obtained
T
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