Huang Tsung-Lin, Peng Kang-Ping, Chen Ching-Lun, Lin Horng-Chih, George Tom, Li Pei-Wen
Department of Electronics Engineering and Institute of Electronics, National Chiao Tung University, HsinChu, Taiwan (R.O.C.).
Sci Rep. 2019 Aug 5;9(1):11303. doi: 10.1038/s41598-019-47806-0.
We report the novel tunability of the diameters and spacings of paired Ge double quantum dots (DQDs) using nano-spacer technology in combination with selective oxidation of SiGe at high temperature. Pairs of spherical-shaped Ge QDs were formed by the selective oxidation of poly-SiGe spacer islands at each sidewall corner of the nano-patterned SiN/poly-Si ridges. The diameters of the Ge spherical QDs are essentially determined by geometrical conditions (height, width, and length) of the nano-patterned spacer islands of poly-SiGe, which are tunable by adjusting the process times of deposition and etch back for poly-SiGe spacer layers in combination with the exposure dose of electron-beam lithography. Most importantly, the separations between the Ge DQDs are controllable by adjusting the widths of the poly-Si/SiN ridges and the thermal oxidation times. Our self-organization and self-alignment approach achieved high symmetry within the Ge DQDs in terms of the individual QD diameters as well as the coupling barriers between the QDs and external electrodes in close proximity.
我们报道了利用纳米间隔层技术结合高温下SiGe的选择性氧化，实现对成对锗双量子点（DQD）直径和间距的新型可调谐性。通过在纳米图案化的SiN/多晶硅脊的每个侧壁角处对多晶硅锗间隔层岛进行选择性氧化，形成了成对的球形锗量子点。锗球形量子点的直径基本上由多晶硅锗纳米图案化间隔层岛的几何条件（高度、宽度和长度）决定，这些条件可通过调整多晶硅锗间隔层的沉积和回蚀工艺时间以及电子束光刻的曝光剂量来调节。最重要的是，锗双量子点之间的间距可通过调整多晶硅/ SiN脊的宽度和热氧化时间来控制。我们的自组织和自对准方法在锗双量子点内实现了高对称性，包括单个量子点直径以及量子点与紧邻外部电极之间的耦合势垒。
