NER: Molecular Electronics and Spintronics in Self-Assembled Monolayer Devices

这项NER计划是有机材料科学和化学(Burtman)、光学、光电子学和磁传输(VarDeny)以及设备物理(两者)等领域不同专业的研究人员共同努力的成果。这两家联合PI.已经合作了两年，并成功地建立了一套用于不断增长的自组装单层膜(SAM)的装置。因此，我们在拟议研究的各个方面都很有经验。智力优势：这项提议的目标是展示和研究分子器件中的电子和自旋电子学过程，分子器件由具有锚定硫醇端基的导电和绝缘分子的SAM混合物制成，在具有一维传输的孤立分子和具有二维传输的聚集体之间的传输过程进行定制。SAM二极管将由分子导线(1，4苯-二甲基硫醇，Me-BDT)和分子绝缘体(五硫醇，PT)和分子绝缘体(五硫醇，PT)和分子绝缘体(五硫醇，PT)和金属铁磁(FM)和包括金和钴的非FM电极上的导线/绝缘体按不同的比例按不同的比例混合而成。在r10-3时，Me-BDT分子应该被隔离在绝缘的PT基质中，而在r0.1时，它们将形成二维(2D)聚集体。我们建议使用借鉴其他应用科学分领域的分子标签滴定技术来检查(I)Me-BDT与相反电极的成键；(Ii)Me-BdT分子的表面密度，以及(Iii)Me-BdT分子聚集体的形成。这些测量包括光学吸收、振动光谱、AFM显微镜和电化学电荷计数。利用所制备的SAM器件，我们将能够从器件的I-V特性和在不同温度下测量的微分电导特性来研究孤立和聚集的Me-BDT导电分子的电荷传输特性。此外，还将使用磁阻(MR)测量来获得Me-BDT分子和聚集体的自旋输运特性，其中将研究钴基SAM器件的I-V特性作为外部磁场的函数。通过这些测量，我们希望能够清楚地区分基于孤立分子线的器件和基于2D分子线聚集体的器件；预计在特定的RC值处会发生相变。生长SAM所需的所有设备以及器件制造和测试所需的设置都已经在我们的实验室中。我们已取得初步结果，显示拟议研究的可行性。更广泛的影响：这些初步研究如果成功，将展示一种使用SAM设备研究单分子和显示电荷离域的分子聚集体中电荷和自旋输运的替代方法。我们的测量具有使用可靠的测量技术大幅推进分子电场的潜力。此外，整合我们大量的实验工作，包括SAM生长、光学、磁光和器件制造、加工和测试，将有助于有效地培养将参与高度跨学科研究项目的博士后助理以及研究生和本科生。这项提案属于纳米设备和系统架构领域。

This NER proposal is a collaborative effort among researchers with diverse expertise in Organic Materials Science and Chemistry (Burtman); Optics, Optoelectronics, and Magneto-transport (Vardeny), and device Physics (both). The two co-PI.s have worked together for two years and have successfully built a set-up for growing self-assembled monolayers (SAM). We are therefore experienced in all aspects of the proposed studies. Intellectual Merit: The goal of this proposal is to demonstrate and study electronic and spintronics processes in molecular devices made of SAM mixtures of conducting and insulating molecules with anchoring thiol end groups, upon tailoring the transport process between isolated molecules with 1D-like transport and aggregates with 2D-like transport. SAM diodes will be fabricated from solution mixtures of molecular wires (1,4 benzene-dimethane-thiol, Me-BDT) with two anchoring thiol end groups, and molecular insulators (pentathiol, PT) with one anchoring thiol end group, at different ratio, r of wires/insulators on metallic ferromagnetic (FM) and non-FM electrodes that include gold and cobalt. At r 10-3 the Me-BDT molecules should be isolated in the insulating PT matrix, whereas they would form two-dimensional (2D) aggregates at r 0.1. We propose to check (i) the Me-BDT bonding to the opposite electrodes; (ii) Me-BDT molecular surface density, and (iii) Me-BDT molecular aggregate formation, using titration techniques of molecular tags that are borrowed from other Applied Science subfields. These measurements include optical absorption, vibrational spectroscopy, AFM microscopy, and electrochemical charge counting. Using the fabricated SAM devices we will be able to study the charge transport properties of isolated and aggregated Me-BDT conducting molecules from the device I-V and differential conductance characteristics, measured at different temperatures. In addition spin transport properties of Me-BDT molecules and aggregates will be also obtained using magnetoresistance (MR) measurements, where the I-V characteristic of Co-based SAM devices will be studied as a function of an external magnetic field. From these measurements we expect to be able to clearly separate devices based on isolated molecular wires from those based on 2D molecular wire aggregates; a phase transition at a certain rc value is anticipated. All the necessary equipment for the SAM growth and set-ups for the device fabrication and testing are already in our laboratory. We have obtained preliminary results that show the feasibility of the proposed studies. Broader Impact: These pilot research studies, if successful would show an alternative method of studying charge and spin transport in single molecules, and in molecular aggregates that show charge delocalization, using SAM devices. Our measurements have the potential to substantially advance the molecular electronic field using a reliable measurement technique. In addition the integration of our large arsenal of experimental efforts, including SAM growth, optics, magneto-optics, and device fabrication, processing and testing, will serve to efficiently educate the post-doctoral associate, and graduate and undergraduate students who will be involved in the highly interdisciplinary research projects. This proposal is in the subfield of Nanoscale Devices and System Architecture.