Light illumination effects on floating gate memory with Ge nanocrystals in HfO2

The influence of light illumination on the programming of a capacitor floating gate memory based on Ge nanocrystals in HfO2 was studied. The capacitor was fabricated on a c-Si substrate by magnetron sputtering deposition of a layer sequence of HfO 2 /Ge-HfO 2 /HfO 2 and post-growth rapid thermal annealing for nanocrystals formation at 600 oC. The illumination of the structure was performed through a semi-transparent Au contact (20% transparency). A maximum value of the light-induced change of 90% in C-V curve was obtained for 5 mW/cm2 illumination during +5 V writing programming. The effect of the light exposure on the relative change of the C-V curve can be increased by reducing the writing time at 1 min.