Kelvin Probe: Non-contact and non-destructive surface analytical tool: basic principles.
ABSTRACT :
The surface of metals and semiconductors, though advanced on technology-front, still pose unique challenges in the understanding. Most of the versatile analytical probes give abundant information but the tools but they do modify the surfaces. The Kelvin probe is a most powerful non-contact method of evaluating the metal and semiconductor surfaces; the surface remains virgin even after the measurement. Kelvin probe machine measures the surface work-function.
The basic principle of the method is : when two metals of different (electro-chemical potentials) work-functions are electrically connected , the electron flow takes place from a metal of a higher work-function to that of a metal with a lower work-function; electrons flow only if there is a potential. This potential is created by the electrical contact: so, it is known as Contact Potential Difference (CPD). From CPD, surface work function can be evaluated. Surface work function, though not a unique,
The Kelvin probe technique is employed in several areas of investigation based on the electronic behaviour of surfaces of several materials: mechanical and tribological properties, interfacial phenomena, adhesion, corrosion, photocatalytic activity, surface defects and morphology and bacterial biofilm adherence. Results from surface modification of transparent and conducting thin films and bio-medical implants will be presented.