篇題：Tunable diameter and spacing of double Ge quantum dots using highly-controllable spacers and selective oxidation of SiGe
文章出處：Scientific Reports, vol. 9, 11303 (2019)
作者：T. L. Huang, K. P. Peng, H. C. Lin, T. George, and P. W. Li
任職單位及部門：Department of Electronic Engineering, National Chiao Tung University
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 Si0.85Ge0.15 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 Si3N4/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/Si3N4 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
文章摘要：
我們運用奈米襯壁技術結合矽鍺合金在高溫下的選擇性氧化，提出了製作成對鍺雙耦合量子點 (DQD)的方法。此方法具有高度掌控鍺量子點 的直徑和量子點之間間距的可調性。製作鍺雙耦合量子點的方法主要是以微影定義製作單晶矽脊為基礎，運用化學氣相沉積成長披覆性極佳的氮化矽以及複晶矽鍺合金後，再以直接回蝕刻，在單晶矽脊的每個側壁角處製作出複晶矽鍺襯壁島。接著，運用高溫熱氧化，可以形成成對的球狀鍺雙耦合量子點。 球狀鍺量子點的直徑主要由複晶矽鍺襯壁島的高度、寬度和長度決定之。這些幾何條件可以通過調整複晶矽鍺的沉積和回蝕工藝時間進行調變。最重要的是，鍺雙耦合量子點 之間的間隔可以通過調整 單晶矽脊的寬度和熱氧化時間來控制。我們所提出的自組織鍺雙耦合量子點可以透過自然形成的二氧化矽位障以及單晶矽脊耦合勢壘，自我對準至外部電極，為量子位元的製作提供了核心積木技術。