I reached out to a few folks to be sure to answer your question properly. Roger Stewart, a patent expert in the radio frequency identification field, says all chips he knows of use EEPROM memory, not Flash.
Alien Technology, a provider of ultrahigh-frequency (UHF) RFID systems, prefers not to discuss its chip architecture publically, but reports that its chip “really does not fit 100 percent into either camp (Flash or EEPROM), but probably is more EEPROM-like.”
In addition, Fujitsu recently introduced RFID transponders that employ ferroelectric random access memory (see Fujitsu Announces Availability of New High-Memory RFID Chip). FRAM chips utilize a ferroelectric layer instead of a dielectric layer, in order to achieve non-volatility. FRAM offers fast write speeds and high memory capacity, and such chips can withstand gamma radiation and electron beams.
—Mark Roberti, Founder and Editor, RFID Journal
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