An autonomous environmental monitoring buoy deployed in the Southern Ocean uses a low-power microprocessing unit containing billions of integrated silicon MOSFETs.
State the name or chemical formula of the insulating layer situated directly beneath the gate electrode in an enhancement-mode N-channel MOSFET that prevents gate current from flowing, leading to its extremely high input resistance.
The buoy's microprocessor chip contains 3.2 × 108 integrated MOSFETs. A discrete (individual) MOSFET of a similar class exhibits a typical standby leakage current, IDSSI_{DSS}IDSS, of 8.0 nA8.0\text{ nA}8.0 nA.
The scientific instrument is powered by a backup battery with a capacity of 650 mAh. A fully charged battery with a capacity of 1 Ah allows 3600 C of charge to flow. The operational specification requires the buoy to remain on standby during the polar winter for 120 days120\text{ days}120 days on a single charge.
By calculating the potential standby duration of the buoy if all 3.2 × 108 integrated transistors on the chip leaked 8.0 nA8.0\text{ nA}8.0 nA each, discuss why the actual leakage current of the integrated MOSFETs on the silicon chip must be vastly smaller than that of the discrete device.
