Self-assembled integration technologies of silicon quantum dots toward future NeoSilicon quantum information devices

采用脉冲气体甚高频等离子体法制备了直径为-8 nm的纳米硅点，并沉积在衬底上。我们通过超声处理将沉积的硅片浸入乙醇中，成功地制备了纳米硅点分散液。然后，我们将少量的溶液滴在其他基质上，并将其烘干。在醇的蒸发过程中，纳米硅点通过侧向毛细管弯月面作用力在溶液中组装。用这种方法得到了网点的二维组装。此外，我们还发展了一种新的自下而上的高密度组装纳米硅量子点的技术，该技术基于Langmuir-Blodgett(LB)技术。结果表明，以氯仿(CHCl_3)和HMDS([(CH_3)_3Si]_2NH)为溶剂适合于制备纳米硅。利用LB法实现了纳米硅点的高密度组装，研究了纳米硅点在具有纳米图形的绝缘体衬底上的组装，成功地实现了纳米硅点在纳米电极之间的团簇桥联，间距最小为20 nm。将自上而下的纳米光刻技术和自下而上的自组装技术相结合，可能为未来量子信息器件的应用提供一种新的制备纳米硅结构的方法。我们还尝试了将nc-Si量子点与单电子晶体管(SET)进行集成。利用电子束光刻技术在SET岛和栅极之间的狭窄区域制作了抗蚀剂空穴。经过nc-Si沉积和剥离过程后，我们观察到nc-Si量子点只在抗蚀剂空穴区域与衬底直接接触。从等效电路模拟和三维电容分析中我们发现，纳米硅量子点有助于有效地移动库仑振荡峰线，并且可以感受到微妙的电荷极化显著的移动。

Nanocrystalline Si dots with a diameter of -8 nm were fabricated by using pulsed gas VHF plasma process and deposited on the substrate. We have successfully prepared the nc-Si dot dispersion solution by immersing the deposited wafer into alcohols with ultra sonic treatment. We then dropped a small volume of the solution onto other substrates and dried it. During the evaporation of alcohols the nc-Si dots were assembled in the solution via the lateral capillary meniscus force. Two-dimensional assembly of the dots was obtained by this method. Furthermore, we developped a new bottom-up technique for high-density assembly of the nc-Si quantum dots based on the Langmuir-Blodgett (LB) technique. We found that the solvent consists of chloroform (CHCl_3) and HMDS ([(CH_3)_3Si]_2NH) was suitable to the LB method for nc-Si. High density assembly of dots was obtained by using the LB method.We examined the assembly of the nc-Si dots on the silicon-on-insulator substrates with nanoscale patterning and succeeded in making the nc-Si dots cluster bridging between the nano-electrodes with a gap of as small as 20 nm. Combining the top-down nanolithography and bottom-up self-assembly may provide a new method to fabricate nanoscale Si structures for the future quantum information device applications. We also tried to integrate of nc-Si quantum dots with the single electron transistor (SET) A resist hole was prepared in the narrow region between the SET island and gate electrodes using the electron beam lithography. After the nc-Si deposition and lift-off processes, we observed that nc-Si QDs contacted directly to the substrate only in the resist hole area. From the equivalent circuit simulation and 3D capacitance analysis, we found that nc-Si QDs help to shift the Coulomb oscillation peak lines effectively and subtle charge polarization can be sensed as their remarkable shift.