Performance enhancement in p-channel charge-trapping flash memory devices with Si/Ge super-lattice channel and band-to-band tunneling induced hot-electron injection

P-channel charge-trapping flash memory devices with Si, SiGe, and Si/Ge super-lattice channel are investigated in this work. A Si/Ge super-lattice structure with extremely low roughness and good crystal structure is obtained by precisely controlling the epitaxy thickness of Ge layer. Both programming and erasing (P/E) speeds are significantly improved by employing this Si/Ge super-lattice channel. Moreover, satisfactory retention and excellent endurance characteristics up to 106 P/E cycles with 3.8 V memory window show that the degradation on reliability properties is negligible when super-lattice channel is introduced.

► A super-lattice structure is proposed to introduce more Ge content into channel.
► Super-lattice structure possesses low roughness and good crystal structure.
► P-channel flash devices with Si, SiGe, and super-lattice channel are investigated.
► Programming/erasing speeds are significantly improved.
► Reliability properties can be kept for device with super-lattice channel.