A nano-floating gate memory capacitor consisting of a stack of 3 nm-thick HfAlOx tunneling layer, self-organized Ag nanocrystals (NCs), and a 6 nm-thick HfAlOx control layer, has been fabricated on compressively strained p-type Si83Ge17/Si(100) substrates by radio-frequency magnetron sputtering. The Ag-NCs with a size of 5-8 nm and a density of 5.7 x 10(12)/cm(2) are well dispersed in the amorphous HfAlOx matrix. Counter clockwise hysteresis capacitance-voltage curve with a memory window of similar to 2 V, corresponding to a charge storage density of about 1.3 x 10(13) electrons/cm(2), is observed in this memory capacitor. The accumulation capacitance of this memory capacitor has no obvious decrease during electrical stressing process within a period of 10(4) s, but the memory window gradually becomes narrower, and only 54% stored charges are retained in the Ag-NCs after 10(5) s stressing. Defect-enhanced Poole-Frenkel tunneling is found to be responsible for the degradation of memory properties. (C) 2014 Elsevier B.V. All rights reserved.