Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185-1056, USA.
Nanotechnology. 2010 Feb 26;21(8):85201. doi: 10.1088/0957-4484/21/8/085201. Epub 2010 Jan 26.
Electronic devices that are designed to use the properties of single atoms such as donors or defects have become a reality with recent demonstrations of donor spectroscopy, single photon emission sources, and magnetic imaging using defect centers in diamond. Ion implantation, an industry standard for atom placement in materials, requires augmentation for single ion capability including a method for detecting a single ion arrival. Integrating single ion detection techniques with the single donor device construction region allows single ion arrival to be assured. Improving detector sensitivity is linked to improving control over the straggle of the ion as well as providing more flexibility in lay-out integration with the active region of the single donor device construction zone by allowing ion sensing at potentially greater distances. Using a remotely located passively gated single ion Geiger mode avalanche diode (SIGMA) detector we have demonstrated 100% detection efficiency at a distance of >75 microm from the center of the collecting junction. This detection efficiency is achieved with sensitivity to approximately 600 or fewer electron-hole pairs produced by the implanted ion. Ion detectors with this sensitivity and integrated with a thin dielectric, for example a 5 nm gate oxide, using low energy Sb implantation would have an end of range straggle of <2.5 nm. Significant reduction in false count probability is, furthermore, achieved by modifying the ion beam set-up to allow for cryogenic operation of the SIGMA detector. Using a detection window of 230 ns at 1 Hz, the probability of a false count was measured as approximately 10(-1) and 10(-4) for operation temperatures of approximately 300 K and approximately 77 K, respectively. Low temperature operation and reduced false, 'dark', counts are critical to achieving high confidence in single ion arrival. For the device performance in this work, the confidence is calculated as a probability of >98% for counting one and only one ion for a false count probability of 10(-4) at an average ion number per gated window of 0.015.
电子设备设计利用单个原子的特性，如供体或缺陷，最近在供体光谱学、单光子发射源以及使用钻石缺陷中心的磁成像方面的演示已经成为现实。离子注入是材料中原子放置的行业标准，需要增强单离子能力，包括一种检测单离子到达的方法。将单离子检测技术与单个供体器件结构区域集成，可以确保单离子到达。提高探测器的灵敏度与控制离子的离散度以及提供更大的灵活性有关，这种灵活性通过允许在潜在更远的距离处进行离子感应，与单个供体器件结构区域的有源区域进行布局集成。我们使用远程无源门控单离子盖革模式雪崩二极管（SIGMA）探测器，在与收集结中心的距离大于 75 微米的地方，已经证明了 100%的检测效率。这种检测效率是通过对大约 600 个或更少的由注入离子产生的电子-空穴对的灵敏度来实现的。具有这种灵敏度的离子探测器与薄电介质集成，例如 5nm 的栅氧化层，使用低能 Sb 注入，其末端射程离散度将小于 2.5nm。通过修改离子束设置以允许 SIGMA 探测器在低温下运行，进一步显著降低了误计数的概率。使用 1Hz 时 230ns 的检测窗口，在大约 300K 和大约 77K 的工作温度下，分别测量到大约 10(-1)和大约 10(-4)的误计数概率。低温操作和减少虚假的、“暗”计数对于实现对单离子到达的高置信度至关重要。对于这项工作中的器件性能，置信度的计算是在平均每个门控窗口的离子数为 0.015 的情况下，误计数概率为 10(-4)时，计数一个且仅一个离子的概率大于 98%。
