Abstract
The structure of SiGe nanocrystals embedded in Al 2 O 3 formed by sequential deposition of Al 2 O 3 /Si/Ge/Al 2 O 3 and a subsequent annealing was confirmed by transmission electron microscopy and energy dispersive spectroscopy (EDS), and its application for write-once-read-many-times (WORM) memory devices was explored in this study. By applying a -10 V pulse for 1 s, a large amount of holes injected from Si substrate are stored in the nanocrystals and consequently, the current at +1.5 V increases by a factor of 10 4 as compared to that of the initial state. Even with a smaller -5 V pulse for 1 μs, a sufficiently large current ratio of 36 can still be obtained, verifying the low power operation. Since holes are stored in nanocrystals which are isolated from Si substrate by Al 2 O 3 with good integrity and correspond to a large valence band offset with respect to Al 2 O 3 , desirable read endurance up to 10 5 cycles and excellent retention over 100 yr are achieved. Combining these promising characteristics, WORM memory devices are appropriate for high-performance archival storage applications. © 2012 American Institute of Physics.