MOS Capacitors, MOS Transistors, and Charge-Transfer Devices

The chapter has two main parts: the first one addresses the functioning of the MOS capacitor and MOS transistor, considering the case of a p-type substrate. The description of the MOS capacitor is extended to that of the photocapacitor, to be later applied to the case of solid-state imagers. The transistor structure considered in this chapter is simple (i.e., planar); the analysis, however, is carried out in detail, leading to models for the drain current applicable to different functioning regimes of the channel (depletion, weak and strong inversion, saturation). From this, the simpler linear-parabolic model is derived, for both the p- and n-type substrates, necessary to set up the elementary theory of the CMOS inverter. A brief analysis of the scaling rules for MOSFETs is carried out as well. The second part illustrates the functioning of two important types of charge-transfer devices, CCD and CID, along with some applications, of which the most important are in the field of optical sensing. The architecture of imagers using CCD or CID is illustrated, and different aspects of their performance are analyzed.