Method for measuring nm-scale tip-sample capacitance
A method for measuring nm-scale tip-sample capacitance including (a) measuring a cantilever deflection and a change in probe-sample capacitance relative to a reference level as a function of a probe assembly height; (b) fitting out-of-contact data to a function; (c) subtracting the function from capacitance data to get a residual capacitance as a function of the probe assembly height; and (d) determining the residual capacitance at a z-position where the cantilever deflection is zero.
1. A method for measuring nm-scale tip-sample capacitance, said method comprising:
measuring a cantilever deflection and a change in probe-sample capacitance relative to a reference level as a function of a probe assembly height;
fitting out-of-contact data to a function;
subtracting said function from capacitance data to get a residual capacitance as a function of said probe assembly height; and
determining said nm-scale tip-sample capacitance by equating said residual capacitance at a z-position where said cantilever deflection is zero.
2. The method according to claim 1 wherein said function is a smoothly-varying function.
3. The method according to claim 1 wherein said fitting of said out-of-contact data to a function is accomplished using a quadratic fit.
4. The method according to claim 1 where said fitting of said out-of-contact data to a function is accomplished using a linear fit.