Probing the States of Single Molecules for Sensing and Multi-value Memory Applications

闪存存储器用于在移动的电话中存储电话号码、音乐、图片和视频，并且现在也经常用于代替膝上型计算机中的磁性硬盘。这种存储器是非易失性的，即使电池失去所有电荷也能保留信息。消费者不断地希望在他们的便携式电子设备上有更多的存储器，以允许存储更多的视频和音乐，但是闪存已经接近缩放限制，阻止了未来存储器大小的显著增加。闪存由浮栅充电节点组成，其中当节点充电时，单个位的数字信息被存储为“1”，而当节点放电时，单个位的数字信息被存储为“0”。随着浮置栅极尺寸的减小，当电子泄漏出浮置栅极或泄漏到浮置栅极上时，存在更多的误差。这些误差是由于浮置栅极尺寸的变化引起的，仅几个原子层就足以基本上改变将电子隧穿到浮置栅极上或从浮置栅极隧穿离开所需的施加电压。我们改进闪速存储器并允许更小存储器的方法是使用化学产生的分子，以允许电荷作为数字存储器存储，并且由于分子都是相同的，所以它们不会遭受与当前硅浮栅闪速存储器相同的可变性误差。我们的最终目标是使用单分子来实现进一步的扩展，从而旨在增加未来可用的内存量。我们还将研究可以存储多个“0”和“1”的分子，称为多值记忆。这种多值存储器方法允许在单个浮置栅极上存储更多的位，从而允许更高的存储器密度，进一步扩展可以存储在移动的电话或笔记本电脑上的内容。因此，这里开发的技术可用于测量单分子的性质。这具有直接测量单分子的电子性质的潜在应用，允许目前难以实现的分子水平的完全表征。我们相信，这些技术可以使化学、物理、材料科学和工程领域的广泛研究人员受益，从而实现更便宜的纳米级材料表征。

Flash memories are used to store phone numbers, music, pictures and videos in mobile phones and are also frequently now used in place of magnetic hard disks in laptop computers. Such memories are non-volatile retaining information even if a battery looses all charge. Consumers constantly want more memory on their portable electronic devices to allow more video and music to be stored but flash memory is already close to the scaling limits preventing significant increases to memory sizes in the future. A flash memory consists of a floating gate charge node where the a single bit of digital information is stored as a "1" when the node is charged and "0" when the node is discharged. As the floating gate is reduced in size, there are more errors when electrons leak out of or onto the floating gate. These errors result from variation in floating gate size by just a few atomic layers which are sufficient to substantially change the applied voltage required to tunnel electrons onto or off the floating gate. This limit has been reached with present production.Our approach to improve flash memory and allow smaller memories is to use molecules which are produced chemically to allow charges to be stored as the digital memory and as the molecules are all identical, they do not suffer the same variability errors as the present silicon floating gate flash memories. Out ultimate aim is to use single molecules to enable further scaling thereby aiming to increase the amount of memory available in the future. We will also investigate molecules that can store more than "0" and "1" known as multi-valued memory. This multi-valued memory approach allows more bits to be stored on a single floating gate thereby allowing higher memory density expanding further what could be stored on a mobile phone or laptop computer.The approach we are taking requires the ability to measure the state an electron occupies on a single molecule. Therefore the technique developed here could be used to measure the properties of single molecules. This has potential applications for measuring the electronic properties of single molecules directly allowing the full characterisation of the molecular levels which at present is difficult to achieve. We believe these techniques can benefit a wide range of researchers in chemistry, physics, materials science and engineering in achieving far cheaper characterisation of materials at the nanoscale.