Quantitative amplitude-modulation scanning Kelvin probe microscopy via the second eigenmode excitation

Comparing the performance of single and multifrequency Kelvin probe force microscopy techniques in air and water

“…(5) We consider the capacitive terms to be equivalent for different eigenmodes, allowing for a direct division of the electrostatic force harmonics in order to access CPD. Some authors have indicated that the capacitance contribution of the lever differs at higher eigenmodes due to the mode shape of the cantilever [17,60,63]. This would primarily affect the accuracy of CPD for purely electrical modes dependent on C′ as the mechanically coupled modes dependent on C″ have minimal cantilever contribution [101].…”

“…This limits the accessible bandwidth and, therefore, the scanning speed [10]. (3) Higher eigenmodes -by applying the electrical signal to a higher eigenmode, the electrostatic response can be measured simultaneously with topography in a single pass [17,[60][61][62]. Higher eigenmodes typically have poorer SNRs than the fundamental eigenmode since k n increases more rapidly than Q n [60,61].…”

“…(3) Higher eigenmodes -by applying the electrical signal to a higher eigenmode, the electrostatic response can be measured simultaneously with topography in a single pass [17,[60][61][62]. Higher eigenmodes typically have poorer SNRs than the fundamental eigenmode since k n increases more rapidly than Q n [60,61]. However, these modes still offer significant SNR enhancements over off-resonance techniques, higher spatial resolution due to reduced influence of the cantilever to the electrostatic forces [17,60,63], and higher bandwidth than side-band techniques [10,58].…”

“…Higher eigenmodes typically have poorer SNRs than the fundamental eigenmode since k n increases more rapidly than Q n [60,61]. However, these modes still offer significant SNR enhancements over off-resonance techniques, higher spatial resolution due to reduced influence of the cantilever to the electrostatic forces [17,60,63], and higher bandwidth than side-band techniques [10,58]. All modes of KPFM can in principle be applied in any of these scenarios.…”

“…The most common application of KPFM in AFM is CL AM-KPFM on the fundamental eigenmode where a bias feedback loop is employed to cancel the electrostatic force and to extract V CPD [10,60,61]. This single-frequency technique can also be used under OL conditions without a feedback loop using phase-based detection [71], frequency sweeps [40,64,72], or bias modulation [10,52,73].…”