The Synthesis And Characterization Of Intrinsic Germanium Nanowires And The Study Of Their Nonvolatile Memory Properties

One dimensional (1D) semiconductor nanowires are attractive to be the buildingblocks for future nanoelectronics due to the small size and the quantum confinementeffects. For Nanowire-based electronic devices, germanium (Ge) is an excellentcandidate in future electronic application because of its low band gap and high carriermobility.The synthesis of germanium nanowires (Ge NWs) by a traditional method calledvapor-liquid-solid (VLS) has been studied. Au film by sputtering was served ascatalyst, which has a great impact on the diameter of Ge NWs. The thicker of the Aufilm, the larger of the diameter. Different experiment parameters and different spatialposition always lead to different products morphologies. We can synthesize highquality and large area Ge NWs by optimizing the experiment parameters.Intrinsic Ge nanowires with a thick Ge oxide shell were utilized to fabricatenanoscale field-effect transistor (FET) nonvolatile memories, which have a largememory window with high ON/OFF current ratio (~104) due to the small diameter andsurface charge trap. Annealing processes in air condition without additional proceduresafter fabrication of FET device was used to form an appropriate thickness of Ge oxide,which plays a key role as tunnelling dielectric layer to prevent stored surface chargesfrom leaking out. In addition, the good memory retention and the reversiblewrite/read/erase operations indicate the potential applications of these intrinsic GeNWdevices. For further improving the retention capacity of intrinsic FET memory device, Genanowires were decorated with Au and Ag nanoparticles that with a considerableparticles size and appropriate density which confirmed by TEM image. A very largememory window and a little better memory retention was obtained after Au or Agdecoration compared with those device without modification (no metal particles, noannealing). We execute an annealing process to enhance the retention property, whichlead to a weakly effect on devices with Au decoration and an effect of invalidating Agnanoparticles on relevant devices.This work verifies and supplements for the study of Ge NWs synthesis, and alsoprovides a new method and a certain reference for the study of intrinsic Ge NWselectrical properties and the fabrication of nanowires-based nonvolatile memorydevices.