UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-24 23:08
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Conference: Bucharest University Faculty of Physics 2004 Meeting


Section: Solid State Physics and Materials Science


Title:
Simultaneous Evaluation of the Electrical Resistance and Work Function Changes for Resistor Type Sensors


Authors:
Razvan Roescu (1) Irina Dumitriu (1),(2) Adelina Tomescu (1)


Affiliation:
(1) National Institute of Materials Physics

(2) Faculty of Physics, University of Bucharest


E-mail


Keywords:
resistive sensor, Kelvin Probe technique


Abstract:
Sensor optimization by improvement of selectivity and sensibility requires simultaneous investigation of more than one physical parameter, in order to achieve complete understanding of the sensor behaviour. This paper presents a complex investigation of resistive sensors based on Fe2O3 polycrystalline semiconductor, carried out by means of simultaneous investigations of two physical parameters i.e. electrical resistance and work function. The basic principle of solid-state chemical sensor operation is the control of the surface and/or interface potential barrier by adsorbed radicals (surface charge or work function change). This potential change can be produced by different surface interactions and can be read-out by means of Kelvin Probe technique which is a non-destructive, real time investigation method. For compound semiconductors with ionic bonding, the barrier height follows the changes in the work function. As the work function is very sensitive to surface adsorption process, the system which contains compound semiconductors is usually very sensitive. It is known from the theory of adsorption that the surface coverage is usually proportional to work function changes due to adsorption. For resistive type sensors, the simultaneous evaluation of the electrical resistance and work function changes seems physically more reasonable than the simple relative change of the resistance. In this way we can also evaluate the surface potential barrier and electron affinity.