WSEAS Transactions on Systems and Control
Print ISSN: 1991-8763, E-ISSN: 2224-2856
Volume 13, 2018
Interface-State Density in SOI-FET Sensors
Authors: , ,
Abstract: SOI-FET sensors are high-sensitivity analytical devices used for qualitative and quantitative analyses of biological and chemical substances. Decreasing and monitoring of the state density at surface of sensors are the key tasks to increase their sensitivity and reproducibility of parameters of devices. This study aims to apply the threshold voltage method to the SOI-FET sensor/electrolyte systems to determine the density of states in the sensors. For this aim: 1) a dependency between the sensor threshold voltage and the voltage on the electrode immersed in the electrolyte solution was derived, 2) the analytical and experimental dependencies were used to determine the density of states at the sensor surface Dit, 3) errors in Dit related to the uncertainty of values of components of the electrolyte capacitance were determined. It was shown that the uncertainty in the Dit values can be estimated in the process of measuring in solutions with various salt concentrations (1-100 mM). The maximal error in Dit related to the uncertainty of capacitance associated with the charge adsorbed on the sensor surface Qad can be estimated using the well-known design parameters of sensor, the salt concentration in solution and Qad=0. In particular, it was shown that for sensors with typical parameters (the buried oxide thickness of 200 nm, sensor thickness of 30 nm and top-oxide thickness of 2 nm) this error in Dit2 does not exceed 40% in the 100 mM buffer solutions. The threshold voltage method can be successfully applied for monitoring Dit at the stage of cleaning and activation of the sensor surface.
Search Articles
Pages: 514-519
WSEAS Transactions on Systems and Control, ISSN / E-ISSN: 1991-8763 / 2224-2856, Volume 13, 2018, Art. #58