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

采用脉冲气体VHF等离子体技术在衬底上制备了直径约为8 nm的纳米硅点。我们成功地制备了nc-Si点分散液，将沉积的晶片浸没在超声波处理的酒精中。然后我们将少量溶液滴到其他衬底上并干燥，在醇的蒸发过程中，nc-Si点通过横向毛细管弯月面力在溶液中组装。通过这种方法获得了二维组装的点。在此基础上，我们发展了一种新的基于LB技术的自底向上的纳米硅量子点高密度组装技术。实验结果表明，氯仿（CHCl_3）和HMDS（[（CH_3）_3Si]_2NH）组成的溶剂适合LB法制备纳米硅。利用LB方法获得了高密度的纳米硅点组装，我们研究了纳米硅点在绝缘体上硅衬底上的组装，并成功地使纳米硅点簇桥接在纳米电极之间，间隙小至20 nm。将自顶向下的纳米光刻技术与自底向上的自组装技术相结合，有望为未来的量子信息器件提供一种新的制备纳米硅结构的方法。我们还尝试了nc-Si量子点与单电子晶体管（SET）的集成。使用电子束光刻在SET岛和栅电极之间的狭窄区域中制备抗蚀剂孔。在nc-Si沉积和剥离过程之后，我们观察到nc-Si量子点仅在抗蚀剂孔区域中直接接触到衬底。从等效电路模拟和3D电容分析，我们发现，nc-Si量子点有助于有效地移动库仑振荡峰线和微妙的电荷极化，可以感觉到他们的显着移位。

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.