 They used "SONOS" (polysilicon-oxynitride-nitride-oxide-silicon) structure with thickness of silicon dioxide less than 30 Å, and "SIMOS" (stacked-gate injection MOS) structure, respectively, for using "Fowler-Nordheim tunnelling" hot-carrier injection.Around 1976 to 1978, Intel's team, including George Perlegos, made some inventions to improve this tunneling E2PROM technology.In 1978, they developed a 16K (2K word × 8) bit Intel "2816" device with a thin silicon dioxide layer, which was less than 200 Å.