CdTe(001)衬底上平面内HgTe纳米结构的选择区域外延
Selective area epitaxy of in-plane HgTe nanostrcutures on CdTe(001) substrate
AI总结：
本研究针对HgTe对纳米加工敏感的问题，采用选择区域分子束外延在CdTe衬底上生长平面内HgTe纳米结构，实现了良好选择性与电学均匀性，为复杂HgTe基纳米结构制备奠定基础。
摘要：
半导体纳米线被认为在未来电子学、自旋电子学和量子技术应用中发挥关键作用。HgTe是一种潜在候选材料，但其对纳米加工工艺的敏感性限制了自身发展。规避这一障碍的一种途径是选择区域生长技术。本研究利用选择区域分子束外延，在覆盖有图案化SiO₂掩模的半绝缘CdTe衬底上生长了平面内HgTe纳米结构。这些纳米结构的形状由掩模开口沿<110>、<11̄0>或<100>方向的平面内取向、沉积厚度以及生长温度决定。研究可获得数微米长的平面内纳米线，以及网络、菱形结构或环形等更复杂的纳米结构。即使在低至140°C的生长温度和高达0.5 ML/s的生长速率下，仍能实现良好的选择性，掩模上的寄生生长极少。对于<110>取向的纳米线，纳米结构中心呈梯形，具有{111}B晶面，两侧有两个晶粒；而<11̄0>取向的纳米线则呈现{111}A晶面，吸附原子积聚在顶面的两侧。透射电子显微镜观察显示，CdTe衬底与HgTe纳米线之间存在连续的外延关系。采用四点扫描隧道显微镜进行的电阻测量表明，纳米线沿主轴线具有良好的电学均匀性，且输运行为表现为热激活型。这种生长方法为制备用于电子输运测量的复杂HgTe基纳米结构铺平了道路。
英文摘要：
Semiconductor nanowires are believed to play a crucial role for future applications in electronics, spintronics and quantum technologies. A potential candidate is HgTe but its sensitivity to nanofabrication processes restrain its development. A way to circumvent this obstacle is the selective area growth technique. Here, in-plane HgTe nanostructures are grown thanks to selective area molecular beam epitaxy on a semi-insulating CdTe substrate covered with a patterned SiO$_{\mathrm{2}}$ mask. The shape of these nanostructures is defined by the in-plane orientation of the mask aperture along the <$110$>, <$1\bar{\mathrm{1}}0$>, or <$100$> direction, the deposited thickness, and the growth temperature. Several micron long in-plane nanowires can be achieved as well as more complex nanostructures such as networks, diamond structures or rings. A good selectivity is achieved with very little parasitic growth on the mask even for a growth temperature as low as $140$°C and growth rate up to $0.5$ ML/s. For <$110$> oriented nanowires, the center of the nanostructure exhibits a trapezoidal shape with {$111$}B facets and two grains on the sides, while <$1\bar{\mathrm{1}}0$> oriented nanowires show {$111$}A facets with adatoms accumulation on the sides of the top surface. Transmission electron microscopy observations reveal a continuous epitaxial relation between the CdTe substrate and the HgTe nanowire. Measurements of the resistance with fourpoint scanning tunneling microscopy indicates a good electrical homogeneity along the main NW axis and a thermally activated transport. This growth method paves the way toward the fabrication of complex HgTe-based nanostructures for electronic transport measurements.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
