IMPLEMENTATION OF THE TWO-FREQUENCY METHOD FOR MEASURING THE DERIVATIVE OF CAPACITANCE-VOLTAGE CHARACTERISTIC

The article presents an example of the implementation of the two-frequency method for measuring the derivative of the capacitance-voltage characteristic. The authors describe the diagram of the measuring system and the software package for the measurement process control. The article also gives the results of measurements of the capacitance-voltage characteristic and its derivative of the silicon-based metal-insulator-semiconductor structure. The qualitative differences between the derivatives of the capacitive characteristics of the metal-insulator-semiconductor structure were obtained as a result of numerical differentiation and its direct measurement by the two-frequency method. The authors offer an explanation for this difference.

Dependence of field-effect biosensor sensitivity on photo-induced processes in Si and its conductivity type

The effect of photoelectron processes in n-Si and p-Si on the glucose sensitivity of a capacitive field-effect biosensor based on electrolyte/oxide/semiconductor structure was investigated. We obtained that illumination of n-Si/SiO2/PEI structure during the GOx adsorption increases the glucose sensitivity by three times compare to GOx adsorption in the dark. In contrast, p-Si illumination during the GOx adsorption led to a decrease in sensor sensitivity from 2.9 mV/mM to 2.2 mV/mM. The result is explained by a change in the density of immobilized GOx molecules due to a change in the electrostatic forces of attraction under illumination and stabilization of the photo-generated charge on the surface electronic states of the Si/SiO2 and SiO2/PEI interfaces after illumination.