MRI: Development of Molecular Beam Expitaxy Apparatus for Growth of Two Dimensional Electron Gas Systems with Mobility of 100,000,000 cm2/Vs

技术摘要：该项目的目标是构建一种新的分子束外延（MBE）机器，专门用于生产前所未有的纯度和质量的半导体异质结构。该结构将被设计成在低温下产生自由载流子迁移率超过100,000,000 cm2/Vs的二维电子系统（2DES）样品。在设想的低水平化学和结构杂质中，自由的二维电子将主要通过多体库仑相互作用相互作用。这些样品的可用性将使对凝聚态物理中多体现象的广泛基本问题的探究达到前所未有的水平。在过去，随着二维异质结构质量的提高，新的物理学被发现，这导致了两次诺贝尔奖。这些高质量的2DES也有望成为下一代技术的重要组成部分。它们是至关重要的，例如，在检查量子计算中的拓扑方法。载流子迁移率是半导体晶体质量的直接指标。最近的实验表明，目前记录的36,000,000 cm2/Vs的二维电子迁移率可能受到GaAs导电通道内残留化学杂质的限制。这些杂质可能来自多个来源：真空排气和MBE机器中含有熔融元素源的炉部件的破裂，元素源本身的化学杂质，以及MBE室和基材加热设备的泄漏或排气。在新机器中，改进的真空泵和新型真空低温泵的引入将大大降低临界杂质的水平。根据最近的结果和计算，我们预测新机器将能够生长出载流子迁移率超过1亿平方厘米/秒的样品。摘要：本课题的目标是研制一种新的晶体生长机器，专门用于生产具有记录质量和纯度的半导体晶体。在目前的晶体中，自由的传导电子会从固定的残余化学杂质或邻近的传导电子中散射出去。有了这种新的MBE（分子束外延）机器，我们期望生产出杂质水平大大降低的晶体，这样自由电子遭受的主要散射几乎完全来自其他自由电子。电子将能够很容易地移动，而不会碰到固定的杂质，从而导致创纪录的迁移率。在项目标题中。这样的样本将使对凝聚态物理中广泛的基本问题的探究达到前所未有的水平。在过去，随着晶体纯度水平的提高，新的结果被发现，从而获得了1985年和1998年的诺贝尔物理学奖。这种近乎完美的晶体对于远程技术应用也很重要。如当前微芯片萎缩后的计算新方法？摩尔?法律?变得不再可行。将要建造的MBE机器内部是否有真空质量记录？与世界上任何其他晶体生长机器相比，更少的杂质分子将在内部污染生长中的半导体晶体。这项工作将在普林斯顿材料科学与技术研究所和普林斯顿大学电气工程系进行。全美约150名学生和研究人员将直接受益于该项目。

0923369PfeifferPrinceton UniversityTechnical Abstract:The goal of the project is to construct a new molecular beam epitaxy (MBE) machine specifically designed to produce semiconductor hetero-structures of unprecedented purity and quality. The structures will be designed to yield two-dimensional electron system (2DES) samples having free carrier mobilities in excess of 100,000,000 cm2/Vs at cryogenic temperatures. At the low level of chemical and structural impurities envisioned, the free 2D electrons will interact primarily with each other through the many-body Coulomb interaction. The availability of such samples will enable an unprecedented level of inquiry into a broad range of fundamental questions in many-body phenomena in condensed matter physics. In the past, as the quality of 2D hetero-structures has improved, new physics has been discovered, that has led to two Nobel Prizes. These high quality 2DES are also expected to be important for the next generation of technology. They are crucial, for example, in examining topological approaches in quantum computing.Carrier mobility is a direct indication of semiconductor crystalline quality. Recent experiments have revealed the current record 2D electron mobility of 36,000,000 cm2/Vs is likely limited by residual chemical impurities located within the GaAs conducting channel. These impurities can arise from multiple sources: vacuum out-gassing and breakdown of the furnace parts containing the molten elemental sources in the MBE machine, chemical impurities in the elemental sources themselves, and leaks or out-gassing of the MBE chamber and the substrate heating equipment. In the new machine, improved vacuum pumping and the introduction of a novel vacuum cryopump will substantially reduce the levels of critical impurities. Based on recent results and calculations, we predict the new machine will be able to grow samples with carrier mobilities in excess of 100,000,000 cm2/Vs.Layman?s Abstract:The goal of the proposed project is a new crystal growth machine specifically designed to produce semiconductor crystals of record quality and purity. In present day crystals the free conduction electrons scatter off fixed residual chemical impurities, or off the neighboring conduction electrons. With this new MBE (Molecular Beam Epitaxy) machine we expect to produce crystals with strongly reduced impurity levels, so that the dominant scattering that the free electrons suffer will almost exclusively be from other free electrons. The electrons will be able to easily move about without running into fixed impurities, thus leading to the record ?mobility? in the project title. Such samples will enable an unprecedented level of inquiry into a broad range of fundamental questions in condensed matter physics. In the past, as crystal purity levels have improved, new results were discovered which led to Physics Nobel Prizes in 1985, and 1998. Such near-perfect crystals are also important for long range technological applications ? such as new approaches to computing after the current shrinking of microchips according to ?Moore?s Law? becomes no longer feasible. The MBE machine to be constructed will have record quality of vacuum inside ? fewer impurity molecules will be inside to contaminate the growing semiconductor crystal than in any other crystal growth machine in the world. The work will take place at the Princeton Institute for the Science and Technology of Materials and the Department of Electrical Engineering at Princeton University. About 150 students and researchers across the US will directly benefit from this project.