Specific Process Knowledge/Characterization/AFM: Atomic Force Microscopy/KPFM: Difference between revisions
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To get the work function of the your sample of interest, you need to find the work function of the tip as what you measure with KPFM is the work function difference between the tip and the sample. | To get the work function of the your sample of interest, you need to find the work function of the tip as what you measure with KPFM is the work function difference between the tip and the sample. | ||
Measured surface potential = Work funtion (Tip) - Work function (sample) | Measured surface potential = Work funtion (Tip) - Work function (sample) | ||
So | So | ||
Work function (Tip) = Measured surface potential*e + Work function (sample) | Work function (Tip) = Measured surface potential*e + Work function (sample) | ||
When measurening on the gold to fin the work function of the tip: | When measurening on the gold to fin the work function of the tip: | ||
Work function (Tip) = Measured surface potential*e + 5.10eV | Work function (Tip) = Measured surface potential*e + 5.10eV | ||
for example: | for example: | ||
Once we measured the potential -0.514 V on the gold. There the tip work function is: | Once we measured the potential -0.514 V on the gold. There the tip work function is: | ||
Work function (Tip) = -0.514 V * e + 5.10 eV = 4.586 eV | Work function (Tip) = -0.514 V * e + 5.10 eV = 4.586 eV | ||
The value can be typed into the workspace and after that the potential window will show you the work function. | The value can be typed into the workspace and after that the potential window will show you the work function. | ||
The accuracy of your results are limited by the accuracy of the value you use for calibration. It is also limited by the state of the tip. If the tip radius change after the calibration this will affect your results and the tip should be calibrated again. Other things to consider is that the sample surface must be grounded to the stage. Here you can use Al-tape from the surface of the your sample (be very careful not to hit the tape with the AFM probe. | The accuracy of your results are limited by the accuracy of the value you use for calibration. It is also limited by the state of the tip. If the tip radius change after the calibration this will affect your results and the tip should be calibrated again. Other things to consider is that the sample surface must be grounded to the stage. Here you can use Al-tape from the surface of the your sample (be very careful not to hit the tape with the AFM probe. | ||