Formation of ZnO Nanoparticles by Atomic Layer Deposition for the Nonvolatile Memory Thin-Film Transistor Applications

A low-temperature atomic-layer-deposition (ALD) process for the formation of ZnO nanoparticles (NPs) was demonstrated, in which the ALD temperature and cycles for diethylzinc precursor were controlled to be 160 degrees C and 20 cycles. The size and areal density of ZnO NPs were confirmed to be approximately 33 nm and 3x10(9) cm(-2), respectively. Nonvolatile memory thin-film transistors were fabricated by employing the ZnO NPs as charge-trap centers for memory operations. The memory window was found to increase from 0.6 to 17.8 V with increasing the ALD cycles from 5 to 20. On- and off-program operations were also confirmed even with voltage pulses as short as 1 mu s.