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We propose and investigate a novel metal/SiO2/Si3N4/SiO2/SiGe charge trapping flash memory structure (named as MONOS), utilizing SiGe as the buried channel. The fabricated memory device demonstrates excellent program-erasable characteristics attributed to the fact that more carriers are generated by the smaller bandgap of SiGe during program/erase operations. A flat-band voltage shift 2.8 V can be obtained by programming at +11 V for 100 μs. Meanwhile, the memory device exhibits a large memory window of ∼7.17 V under ±12 V sweeping voltage, and a negligible charge loss of 18% after 104 s’ retention. In addition, the leakage current density is lower than 2.52 × 10−7 A·cm−2 below a gate breakdown voltage of 12.5 V. Investigation of leakage current-voltage indicates that the Schottky emission is the predominant conduction mechanisms for leakage current. These desirable characteristics are ascribed to the higher trap density of the Si3N4 charge trapping layer and the better quality of the interface between the SiO2 tunneling layer and the SiGe buried channel. Therefore, the application of the SiGe buried channel is very promising to construct 3D charge trapping NAND flash devices with improved operation characteristics. [ABSTRACT FROM AUTHOR]

A novel high-κ Al2O3/HfO2/Al2O3 nanolaminate charge trapping memory capacitor structure based on SiGe substrates with low interface densities is successfully fabricated and investigated. The memory capacitor exhibits excellent program-erasable characteristics. A large memory window of ∼4 V, a small leakage current density of ∼2 × 10−6 Acm−2 at a gate voltage of 7 V, a high charge trapping density of 1.42 × 1013 cm−2 at a working voltage of ±10 V and good retention characteristics are observed. Furthermore, the programming (at 10 V for 10 μs) and erasing speeds (at −10 V for 10 μs) of the fabricated capacitor based on SiGe substrates are significantly improved as compared with counterparts reported earlier. It is concluded that the high-κ Al2O3/HfO2/Al2O3 nanolaminate charge trapping capacitor structure based on SiGe substrates is a promising candidate for future nano-scaled nonvolatile flash memory applications. [ABSTRACT FROM AUTHOR]