The objective of this work is to explore the capability of a charge trapping control loop to continuously compensate charge induced by ionizing radiation in the dielectric of MOS capacitors. To this effect, two devices made with silicon oxide have been simultaneously irradiated with gamma radiation: one with constant voltage bias, and the other working under a dielectric charge control. The experiment shows substantial charge trapping in the uncontrolled device whereas, at the same time, the control loop is able to compensate the charge induced by gamma radiation in the second device.
Dominguez, M.; Bheesayagari, C.; Gorreta, S.; Lopez, G.; Martin, I.; Blokhina, E.; Pons, J. IEEE transactions on industrial electronics Vol. 64, num. 99, p. 1-7 DOI: 10.1109/TIE.2016.2645159 Data de publicació: 2016-12-26 Article en revista
This paper presents an active control of C-V characteristic for MOS capacitors based on Sliding Mode control and sigma-delta-modulation. The capacitance of the device at a certain voltage is measured periodically and adequate voltage excitations are generated by a feedback loop to place the C-V curve at the desired target position. Experimental results are presented for a n-type c-Si MOS capacitor made with silicon dioxide. It is shown that with this approach it is possible to shift horizontally the C-V curve to the desired operation point. A physical analysis is also presented to explain how the C-V horizontal displacements can be linked to charge trapping in the bulk of the oxide and/or in the silicon-oxide interface. Finally, design criteria are provided for tuning the main parameters of the sliding mode controller.