Charge storage in a metal-oxide-semiconductor capacitor containing cobalt nanocrystals

摘要

Self-assembled cobalt (Co) nanocrystals on ultra-thin silicon dioxide layer were fabricated by in situ annealing Co ultrathin films deposited with Co effusion cell in a molecular-beam-epitaxy chamber. The resultant nanocrystals obtained at the optimized annealing temperature are around 3-4 nm in diameter with dot density of about 1 x 10~(12) cm~(-2). The metal-oxide-semiconductor capacitors containing Co nanocrystals exhibit much longer retention times than a Si nanocrystal memory with the same tunneling oxide thickness. This study suggests that Co nanocrystal should be an excellent alternative to replace Si nanocrystal as floating gates for future nonvolatile flash-type memory application.