Partition Method - Ossila FACT1 User Manual

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Partition method

In order to automatically estimate the mobility with the partition method, SuperFACT executes the

following algorithm,

1. The input and output points defining the Transfer Characteristics curves (V

divided into subsets of N point each, with 5≤N≤10 User's defined quantity specified on

Advanced SMU and Acquisition Settings with Partition Method: Set Size control.

2. For each subset, the Best Linear Fit and its respective slope are estimated.

The mobility is then computed using Eq. (4) for the Transfer Characteristic in Linear Regime,

and Eq. (8) for the Transfer Characteristic in Saturation Regime, see figure 26.

3. The resulting mobility

median pints of the data point subsets used to calculate the liner fits.

4. For both linear and saturation regime, the maximum mobility is highlighted on the mobility

plot and reported on the data file providing that the linear fit R-squared parameter is larger

than a User's defined threshold specified on Advanced SMU and Acquisition Settings

through the Partition Method: R-squared control. (The recommended value of R-squared

for this algorithm is 0.99). If no data-point set satisfies this condition, the mobility plot turns

red with an exclamation mark in the plot legend flagging which mobility does not fulfil this

requirement. A warning message flag is also logged in the data file by printing an

acclamation mark next to device number.

For each linear fit, SuperFACT calculates also the Upper and Lower Bounds of the fit at a 0.95

confidence level, see figure 26, whose meaning is the following:

There is a 95% probability that the actual best linear fit lies in the region demarcated by the

upper and lower bounds, where the blue dashed line represent the linear fit bounds

Figure 26. Linear Fit (Red, solid line) and Upper and Lower Bound defining the confidence

interval (dashed blue line) for two subsets of input (Gate Voltages) and measured point (Drain

Current) for TC in Saturation Mode.

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is then plotted as function of the gate voltage, with

, I

) are

GS,i

DS,i

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