The Controllable Growth And Electrical Properties Of The Ultralong Zinc Oxide Nanowires/Nanobelts

In recent years, the preparation and research of one-dimensional (1D) semiconductornanomaterials has attracted considerable attention due to their promising potentional for thefuture applications in a lot of fields such as gas sensor, UV detector, field effect transistor andphotoelectric devices. Ultralong single crystal ZnO nanowires/nanobelts with high specificsurface and crystal quality， which have excellent electrical and thermal transmissionperformance. These advantages make ZnO nanowires/nanobelts suitable for developinghigh-performance nanodevices, and understanding fundamental transport mechanisms ofone-dimensional system. Ultralong ZnO nanowires/nanobelts can increase the probability ofthe successful preparation of nanodevices, and conducive to construct multiple nanodevicesby using the method of pattern. Therefore, ultralong single crystal ZnO nanowires/nanobeltshave important research value for the field effect transistor and photoelectric deviceapplication. Currently, only a few papers have reported the ultralong ZnOnanowires/nanobelts. Ultralong single crystal ZnO nanowires/nanobelts have beensynthesized mainly through the vapor-phase transport method. But how to choose the bestgrowth conditions and ensure its repeatable preparation is the key of the preparation of ZnOnanowires/nanobelts.This paper introduce that the ultralong single crystal ZnO nanowires and nanobelts havebeen synthesized successfully by carbon thermal reduction method through the horizontaltube furnace with double temperature zones. The device has the advantage that it can controlthe inside temperature gradient of the furnace, and can remain stable growing conditions for along time. This can realize the preparation of ultralong ZnO nanowires/nanobelts. Thereaction temperature of the materials would be reduced from1400℃to950℃by carbonthermal reduction method. The best experimental condition was obtained by optimizing thegrowth condition, ultralong single crystal ZnO nanowires, nanobelts and nanocombs wereobtained in a growth process. In this paper, the morphology and structure of the ultralong ZnOnanowires and nanobelts were characterized. The test results show that the length of ZnOnanowires/nanobelts with excelent single crystal structure are more than100um, and thesurface is smooth and uniform.The growth direction of ZnO nanobelts could be controlled by adjusting carrier gas flowrate, and get different growth direction of ZnO nanobelts. Its growth direction is mainlydivided into two kinds: one is perpendicular to the common[0001] direction ([1010]). Theother one，there is a certain angle (θ=40-60°) between the growth and [0001] directions, whichpresents the growth direction along the [303n](n=2-4). On this basis, the ZnO nanobeltswith the [1010] and [303n](n=2-4) direction were synthesized by adjusting the carrier gasflow rate, respectively. The field effect transistors based on the ZnO nanobelts were preparedthrough using mechanical probe transfer method, and measured the electrical properties of thefield effect transistors based on ZnO nanobelts with different growth directions. Measurement results indicated the excellent field effect characteristics of the two kinds of nanobelts. henanobelts growing perpendicular to [1010] direction have the higher field-effect mobilitywith the average value of101cm2V-1s-1.