Building primitive FGMOSFET for educational purposes
These FETs rely on tunneling.
To deposit charge into a bit, the insulation must be very thin, so under the stresses of high_voltage, the probability of electron movement becomes high/certain.
And afterward, with &quot;normal&quot; operating voltage, the probability of electron escaping becomes near zero, so the &quot;bit&quot; remains charged.
Thus you need to build a system with extremely thin insulation, that is of very high quality, very pure.
And with those skills, semiconductor fabs will want to hire you.