Room-Temperature Single Atom Silicon Quantum Electronics

近年来，使用半导体晶体中的单个杂质原子来定义硅中的半导体量子电子开关已经成为可能。这将电子设备的开关“核心”减少到了原子尺度的极限。此外，杂质原子的离散量子态中的电子电荷可以控制在单个电子的水平上，也可以将信息“比特”的大小从数千个减少到几个，甚至是单个电子。这样的“单原子量子点晶体管”(SA-QDT)具有广泛的应用前景，包括超低功耗高比例纳米电子、单电荷/分子传感器、计量标准和量子计算。要实现SA-QDT的广泛、普遍应用，例如在纳米电子学或超高灵敏度传感中，需要室温(RT)操作和大规模可制造性。然而，目前这些器件的潜力仍然没有得到充分的发挥，诸如仅在低温下进行电操作，使用的材料缺乏大规模的器件制造能力，或者与现有的硅电子电路技术不兼容等。最近，我们已经展示了利用电子束光刻技术在~10 nm尺度的Si-SiO_2-Si点接触中嵌入磷(P)掺杂原子的硅SA-QDT的RT操作。现在已经演示了单量子点RT和双量子点RT的耦合操作。这些器件在硅中的制造与传统的大规模硅电子电路纳米制造技术完全兼容。作为对上述工作的补充，我们还展示了使用先进的扫描探针光刻(SPL)技术在精确的原子尺度上定位杂质原子的方法。本项目的中心目标是在硅中开发有用的RT SA-QDT器件、电路和传感器。为了做到这一点，我们建议从目前的单个器件的水平转移到具有~10个器件的“原则证明”RT电路。我们还将开发基于SA-QDT的单分子传感器，利用这些设备对表面电荷在&lt；1e水平变化的敏感性。我们建议使用电子束和扫描探针光刻方法来构建存储单元、逻辑门和单分子传感器电路。我们还将扩展我们的制造方法，使用氢去钝化SPL进行原子精确的纳米制造，以在RT操作的设备中首次建立这种规模的结构精度。将开发从单个器件到电路级别的模拟方法，以建立单原子电子系统的设计规则。该项目的成功完成将实现单原子器件在量子纳米电子电路和单分子传感器方面的潜力，为未来的大规模原子电子技术开辟道路。

In recent years, it has become possible to define semiconductor quantum electronic switches in silicon using individual impurity atoms within a semiconductor crystal. This reduces the switching 'core' of an electronic device to the ultimate, atomic scale limit. Furthermore, electronic charge in the discrete, quantum states of the impurity atom may be controlled at the level of individual electrons, also reducing the size of information 'bits' from many thousands to a few, or even single electrons. 'Single-atom quantum dot transistors' (SA-QDTs) such as these hold great promise for a wide range of applications, including ultra-low power highly scaled nanoelectronics, single charge/molecule sensors, metrological standards and quantum computation. Achieving wide-scale, general application of SA-QDTs, e.g. in nanoelectronics or ultra-high sensitivity sensing, requires both room-temperature (RT) operation and large-scale manufacturability. However, at present the potential of these devices has remained unfulfilled, due to problems such as electrical operation at only cryogenic temperatures, the use of materials lacking large scale device manufacturability, or a lack of compatibility with current silicon electronic circuits technology, etc. Recently, we have demonstrated RT operation in silicon SA-QDTs based on phosphorus (P) dopant atoms embedded in ~10 nm scale Si-SiO2-Si point-contacts, fabricated by electron beam lithography. Both single and double, coupled, QD RT operation have now been demonstrated. The fabrication of these devices in silicon is completely compatible with conventional large-scale, Si electronic circuit nanofabrication technology. In complementary work to the above, we have also demonstrated methods to locate impurity atoms at precise atomic scales using advanced scanning probe lithographic (SPL) techniques.The central aim of this project is to develop useful RT SA-QDT devices, circuits and sensors in silicon. In doing this we propose to move from the present level of individual devices to 'proof-of-principle' RT circuits with ~10 devices. We will also develop single-molecule sensors based on SA-QDTs, exploiting the sensitivity of these devices to changes in surface charge at the level of <1e. We propose to build memory cell, logic gate and single-molecule sensor circuits, using both electron-beam and scanning probe lithographic methods. We will also extend our fabrication methods for atomically precise nanofabrication using hydrogen depassivation SPL, to establish structural precision at this scale for the first time in devices operating at RT. Simulation methods, from the individual device to circuit level, will be developed to establish design rules for single-atom electronic systems. Successful completion of this project will realise the potential of single-atom devices for quantum nanoelectronic circuits and single-molecule sensors, opening the way for a future large-scale atomic electronics technology.