无催化剂条件下长达毫米级的超宽Ga2O3单晶纳米带制备及特性

Preparation and characteristics of ultra-wide Ga2O3 nanoribbons up to millimeter-long level without catalyst

氧化镓(Ga2O3)单晶纳米带由于具有独特的性质在电子器件中具有潜在的应用,然而目前过小的接触面积使得基于这种纳米材料的器件制备变得非常复杂且充满挑战.本文利用碳热还原法,在无催化剂条件下使氧化镓粉末与碳纳米管在高温下反应,生长出不同结构的氧化镓纳米材料,发现了反应温度影响纳米结构的直径和比例的物理机制,并制备出了长达毫米级的超宽β-Ga2O3单晶纳米带,其横向尺寸可达44.3μm.利用透射电子显微镜(TEM)可以观察到纳米带呈单晶结构,进一步拉曼散射光谱(Raman)表明这种方法生长的β-Ga2O3纳米带的应变较小,缺陷密度较低,且室温光致发光谱(PL)显示该氧化镓纳米带在激发波长295 nm下发出425 nm的稳定且高亮度的蓝光.这种生长方法可为未来器件级氧化镓纳米带制备提供有益的参考.

Gallium oxide(Ga2O3) single crystal nanoribbons have the potential applications in electronic devices due to their unique properties. However, the current small surface area makes the fabrication of device based on this nano-material very complex and challenging, and the introduction of catalyst also makes the growth process of Ga2O3 nanomaterial complicated and hard to control. Therefore, it is very important to study the growth method and physical mechanism of Ga2O3 nanoribbon with the larger surface area without catalyst.In this paper, the carbothermal reduction method is used to grow the Ga2O3 nanomaterial. In this paper,the gallium oxide powder mixes with the carbon nanotubes at a mass ratio of 1:1.5 without the catalyst, and then they are put into a high temperature diffusion furnace for the growth of Ga2O3 nanomaterials with different structures on silicon-based substrates by controlling the reaction temperature. In this paper, it is found that the reaction temperature directly affects the diameter and ratio of gallium oxide nanostructures. The reason is that the bonding energy of gallium oxide crystal is different in different crystal directions which leads to the different growth speed. The interface energy along the growth direction is the smallest and the growth speed is the fastest, while the growth speed along the vertical direction is slow. Finally, the crystal gradually grows into nanoriband, nanometer sheet and other structures.In addition, the ultra-wide β-Ga2O3 single crystal nanobelt up to the millimeter level was prepared in this paper. This nanobelt’s lateral dimension is observed to reach 44.3 μm under the scanning electron microscope(SEM), and the transmission electron microscope(TEM) is used to confirm that the nanoribbons have a single crystal structure. Further, Raman spectroscopy(Raman) shows that the β-Ga2O3 nanoribbons grown by this method have the smaller strain and the lower defect density. Additionally, the room temperature photoluminescence spectrum(PL) test shows that the gallium oxide nanoribbon emits a stable and highbrightness blue light at 425 nm at the excitation wavelength of 295 nm. This growth method can provide a useful way for the preparation of device-level gallium oxide nanoribbons in the future.