Topic 5 min read

Scanning Probes & Materials Research

Latest updated: April 22, 2020

Novel and improved materials are essential to improvements in many areas of everyday life. Scanning probe electrochemistry has been used to help answer a number of questions relating to materials as outlined below.

 

Question Technique Information Measured Example
Are contaminants present on Si wafers? If so, where? SKP SKP can be used to measure the work function due to the surface state of a sample without any special sample preparation. When a contaminant is present on the surface of an Si wafer its work function differs from that of clean Si, confirming the presence of contaminants. Performing an SKP area scan of the sample highlights the location of contaminants due to a difference in work function compared to the surrounding area. D. Cavalcoli, et al., Journal of The Electrochemical Society 150 (2003) G456-G460
What are the electronic characteristics of flakes of 2D materials? dc-SECM In feedback mode dc-SECM measures the faradaic current of a redox mediator in solution which interacts with a sample. Positive feedback occurs when a feedback loop is established where a counter reaction occurs away from the probe. For 2D materials this can occur on the flake of interest or connected flakes. These electronic connections of flakes are illustrated by the manner in which the measured current scales with increasing mediator concentration. When the conductivity is related to the interconnectivity of the flakes the measured current does not scale linearly with increasing mediator concentration. This also provides information on the contact resistance between flakes. T. Bourgeteau, et al., The Journal of Physical Chemistry Letters 5 (2014) 4162-4166 O. Henrotte, et al., ChemPhysChem 18 (2017) 2777 – 2781
How do the electrochemical characteristics of grains and grain boundaries in metal alloys, and other materials, compare? dc-SECM The grains and grain boundaries of a material have differing electrochemical activities, which can be probed by dc-SECM. The Faradaic current measured in dc-SECM is related to the sample activity with higher currents reflecting greater activity. Different activities of the grain and grain boundaries of a material will cause different probe currents which can be locally mapped to visualize the grain/grain boundary structure of the sample. C. A. Lill, et al., Journal of Applied Electrochemistry 38 (2008) 1339-1345
ac-SDC In ac-SDC a single frequency impedance measurement can be performed in the droplet electrochemical cell which can be scanned across the surface. Differences in the electrochemical properties of the grain and grain boundaries will be reflected in differing responses to the frequency measurement and will be locally mapped. A. W. Hassel, M. Seo, Electrochimica Acta 44 (1999) 3769-3777
What is the effect of alloy composition on its electronic properties? SKP SKP measures the contact potential difference between the probe and the sample of interest. This is directly related to the work function of the sample. Calibration of the SKP probe allows the effect of alloy composition on the work function to be determined in a non-contact, non-destructive manner. G.-L. Song, D. Haddad, Materials Chemistry and Physics 125 (2011) 548–552
What is the effect of the dopant on the electronic properties of a thin film? SKP The work function is a valuable measure to compare the electronic properties of a material. In SKP the contact potential difference between the probe and the sample can be calibrated to allow comparison of different dopants on the work function of a thin film. S. Huber, et al. Physica Status Solidi A 216 (2016) 1800942

Materials science Materials research dc-SECM SKP ac-SDC