MOS capacitor
In semiconductor electronics, capacitors are built using MOS technology.
MOS capacitors are used in semiconductor memories, shift registers and CCD sensors and consist of different layers of silicon substrate, an oxide layer of silicon dioxide and a metal layer of aluminum. Silicon( Si) and aluminum (Al) form the electrodes of the capacitor, and silicon dioxide( SiO2) forms the dielectric. These integrated capacitors are called MOS capacitors.
The aluminum electrode is often referred to as the gate. Polycrystalline silicon is also used instead of aluminum. The thickness of the dielectric can be only a few nanometers, depending on the requirements.