I am using an FGMOSFET with tunneling gate and control gate as an analog memory for simulation in SPICE. I use -25V to inject electrons into the floating gate and 25V to remove electrons. Everything was going well until I read this paper:http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.27.7816&rep=rep1&type=pdf
and it says
Bidirectional tunneling can be used to add or remove electrons from a floating gate. This solution, however, requires either dual polarity high voltages, or a single polarity high voltage and a means for pulling the floating gate to this voltage when adding electrons, and pulling it near ground when removing them. Both approaches are unattractive. The dual polarity solution has a negative voltage much lower than the substrate potential; the single polarity solution does not support simultaneous memory reading and writing.
With the current technology we have, is this still valid. Are there technologies that allow a higher negative voltage than the substrate. I would really appreciate any help to point me in the right direction. Thanks