Chaize N, Baudry X, Jouneau P-H, Gautier E, Rouvière J-L, Deblock Y, Xu J, Berthe M, Barbot C, Grandidier B, Desplanque L, Sellier H, Ballet P
CEA, LETI, University Grenoble Alpes, 38000 Grenoble, France.
University Grenoble Alpes, CEA, INAC-MEM, 38000 Grenoble, France.
Nanotechnology. 2024 Oct 8;35(50). doi: 10.1088/1361-6528/ad7ff4.
Semiconductor nanowires (NWs) 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 SiOmask. The shape of these nanostructures is defined by the in-plane orientation of the mask aperture along the <110>, <11¯0>, or <100> direction, the deposited thickness, and the growth temperature (GT). Several micron long in-plane NWs 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 GT as low as 140 °C and growth rate up to 0.5 monolayer per second. For <110> oriented NWs, the center of the nanostructure exhibits a trapezoidal shape with {111}B facets and two grains on the sides, while <11¯0> oriented NWs 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 NW. Measurements of the resistance with four-point 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.
半导体纳米线（NWs）被认为在电子学、自旋电子学和量子技术的未来应用中起着至关重要的作用。一种潜在的候选材料是碲化汞（HgTe），但其对纳米制造工艺的敏感性限制了其发展。规避这一障碍的一种方法是选择性区域生长技术。在此，通过选择性区域分子束外延，在覆盖有图案化二氧化硅（SiO₂）掩膜的半绝缘碲化镉（CdTe）衬底上生长面内HgTe纳米结构。这些纳米结构的形状由掩膜孔径沿<110>、<11¯0>或<100>方向的面内取向、沉积厚度和生长温度（GT）决定。可以实现几微米长的面内NWs以及更复杂的纳米结构，如网络、金刚石结构或环。即使在低至140 °C的生长温度和高达每秒0.5个单层的生长速率下，在掩膜上的寄生生长也非常少，从而实现了良好的选择性。对于<110>取向的NWs，纳米结构的中心呈现出具有{111}B面的梯形形状，侧面有两个晶粒，而<11¯0>取向的NWs显示出{111}A面，顶表面侧面有吸附原子积累。透射电子显微镜观察揭示了CdTe衬底与HgTe NW之间的连续外延关系。用四点扫描隧道显微镜测量电阻表明，沿NW主轴线具有良好的电均匀性和热激活输运。这种生长方法为制造用于电子输运测量的基于HgTe的复杂纳米结构铺平了道路。
