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

Abstract

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 oC and 20 cycles. The size and areal density of ZnO NPs were confirmed to be approximately 33 nm and 3×109 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 µs.