Lecture
This lecture addresses the constraints on the oxide layer in MOS structures, focusing on the scenarios of strong inversion and deep depletion. The instructor begins by correcting exercise E10.3, which prompts a discussion on the implications of these conditions for MOS structures, particularly in relation to a p-substrate. The lecture highlights the behavior of voltage across the oxide during deep depletion, noting that a significant voltage drop occurs within the semiconductor. The total voltage drop is consistently defined by VG, leading to a smaller voltage drop across the oxide. As the well fills, the voltage drop in the semiconductor decreases, resulting in a larger electric field in the oxide. The instructor explains that in a CCD cell, when it is empty, the electric field in the oxide is minimal, reducing the risk of breakdown. However, as photocharges accumulate and the well fills, the voltage drop across the oxide increases, heightening the risk of breakdown due to the stronger electric field.