Conductive DPE probe
Among the serious limitations of Electrical Force Microscopy are the sensitivity and signal to noise ratio. Enlargement of the probe tip radius leads to a loss of resolution in both topography and EFM imaging, while it does not always reduce the noise in the maps of electric properties.
The novel DPE probe consists of a special structure of conductive layers, which provides a more stable electrical signal and less noise through some reduction of resolution in the topography image though.Topography, surface potential and dC/dz scans of a fluoroalkane (F12H20) on a Si substrate are presented in Fig. 1. below. As you see the resolution in topography image made using Pt-coated probe (a) is better because the 6.5 nm lamellar structures are clearly resolved and the shape of brighter features is not as rounded as in the image made with the DPE probe(b). Still the better signal-to-noise peformance is provided by the DPE probe (d,f).
Pt coated probe
and cross-section, DPE probe
Pt coated probe
Comparison of AM-FM scans (5kHz-10kHz) of a fluoroalkane layer made using regular Pt coated probe and DPE probe. Scan size 350 nm. DPE probe provides better signal-to-noise performance, while the topography resolution is better with Pt-coated probe. Image courtesy of Sergei Magonov, Agilent Technologies (Agilent 5500 AFM).
Probes of the DPE series has a special structure of conducting layers applied to the tip that improves signal-to-noise ratio with little impact on the resolution.