Photoresponse of LAPS with Different Species Membranes: Modeling and Simulation

• Main Author: Ferdinand GASPARYAN
• Format: Article
• Language: English
• Published: IFSA Publishing, S.L. 2009-12-01
• Series: Sensors & Transducers
• Subjects: LAPS; Photocurrent; Modulated irradiation; Depletion layer
• Online Access: http://www.sensorsportal.com/HTML/DIGEST/december_09/P_548.pdf

Results of modeling and theoretical simulation of the influence of intensity modulated irradiation on the light addressable potentiometric sensors based on electrolyte-insulator-semiconductor and electrolyte-membrane-insulator-semiconductor structures are presented. Theoretical model for measuring a.c. photocurrent is developed based on the assumption that under modulated irradiation conductivity of semiconductor depletion layer is modulated. The electric equivalent a.c. schemes are presented and the measuring a.c. components of photocurrents are calculated. Analytical expressions for photocurrent dependencies from parameters of the semiconductor and insulator, irradiation adsorption coefficient and intensity, gate voltage and pH concentration are presented. Numerical calculations are made for the p-Si/Insulator/Electrolyte and p-Si/Insulator/Membrane/Electrolyte sensors. It is shown that only periodical excitation of any membrane brings to essential changes of the a.c. component of photocurrent.