Ultra-low-energy ion-beam-synthesis of Ge nanocrystals in thin ALD Al2O3 layers for memory applications
Structural and electrical properties of ALD-grown 5 and 7nm-thick Al2O3 layers before and after implantation of Ge ions (1keV, 0.511016 cm?2) and thermal annealing at temperatures in the 7001050C range are reported. Transmission Electron Microscopy reveals the development of a 1nm-thick SiO2-rich layer at the Al2O3/Si substrate interface as well as the formation of Ge nanocrystals with a mean diameter of ?5nm inside the implanted Al2O3 layers after annealing at 800C for 20min. Electrical measurements performed on metalinsulatorsemiconductor capacitors using Ge-implanted and annealed Al2O3 layers reveal charge storage at low-electric fields mainly due to location of the Ge nanocrystals at a tunnelling distance from the substrate and their spatial dispersion inside the Al2O3 layers.
ge nanocrystals ion implantation nanocrystal memory