NER: Hybrid Organic-Inorganic Devices for Future Spintronics Applications

该提案是对纳米科学和工程计划NSF 01-157的响应，属于NER类别。该提案的重点是测试在无机基质上自组装有机单分子膜以控制自旋现象(即磁性)的可行性。这项工作是由UCSB的Gwinn小组和魏兹曼研究所的Naaman小组合作完成的，前者在半导体物理方面拥有专业知识，后者在将有机薄膜(QOTF)组装到无机基板上具有专业知识。在这些混合器件中，具有大电偶极矩的有机分子化学吸附在无机衬底上，形成有组织的、紧密堆积的偶极层。形成吸附体的能量学有利于电子在有机分子和衬底之间的转移，有点类似于场效应器件中的栅极效应，但不需要栅极或栅极绝缘体。这种化学诱导的电荷转移改变了吸附物和底物的电子性质。拟议的可行性实验将测试有机有机吸附在无机物上的混合器件中的自旋相关现象。使用有机材料的优势在于相对容易定制的特性的大的多功能性，其低成本，以及由于可以取代昂贵的高分辨率光刻的自组装工艺而易于生产。自组装的各种有机分子提供了一个化学旋钮，可能使新的有机/无机自旋电子器件成为可能。在这个为期一年的项目中，将进行两个方面的研究：通过有机吸附对砷化镓半导体器件磁性的化学操纵研究；以及在非磁性衬底上研究手性分子有机无机膜的磁性。具有近表面掺锰层的铁磁GaAs异质结将被OOTF覆盖，以测试铁磁半导体中化学控制磁性的可行性。将通过磁测量和磁输运测量来研究OOTF的影响。OOTF在非磁性的GaAs/AlGaAs超晶格侧壁上的吸附将被用来试图改变出现在量子霍尔区的边态的鞘层。OOTF效应的特征将出现在低温磁输运实验中。手性光学传递函数的研究将进一步研究它们先前观察到的吸附在Au上的磁性，以及手性QQTF在吸附到GaAs上时是否保持它们的磁性。

This proposal was received in response to the Nanoscale Science and Engineering initiative, Program Solicitation NSF 01-157, in the NER category. The proposal focuses on testing the feasibility of using self-assembly of organic monolayers onto inorganic substrates to control spin phenomena, namely magnetism. The work is a collaboration between the Gwinn group at UCSB, which has expertise in semiconductor physics, and the Naaman group at the Weizmann Institute, which has expertise in the assembly of organized, organic thin films (QOTF) onto inorganic substrates. In these hybrid devices, organic molecules with large electric dipole moments chemisorb onto an inorganic substrate, forming an organized, close-packed dipole sheet. The energetics of forming the adsorbate favors transfer of electrons between the organic molecules and the substrate, somewhat similar to the effect of gates in field-effect devices, but without the need for a gate or gate insulator. This chemically-induced charge transfer modifies the electronic properties of both adsorbate and substrate.The proposed feasibility experiments will test for spin-related phenomena in hybrid devices of organized organic adsorbates on inorganics. The advantages of using organic material is the large versatility in properties that can be tailored relatively easily, its low cost, and the ease of production due to self-assembling processes that can replace expensive high resolution lithography. The enormous variety of organic molecules that self-assemble provides a chemical ~knob" that may make possible new classes of organic/inorganic spintronic devices.Two lines of investigation will be pursued during this year-long project: studies of chemical manipulation of the magnetic properties of GaAs-based semiconductor devices via the organic adsorbate; and studies of the magnetic properties of organic inonolayers of chiral molecules on non-magnetic substrates. Ferromagnetic GaAs heterostructures with near-surface Mn-doped layers will be covered with OOTF to test the feasibility of chemically controlling magnetism in ferromagnetic semiconductors. The effects of the OOTF will be investigated by magnetometry and by magnetotransport measurements. Adsorption of OOTF onto the sidewalls of non-magnetic GaAs/A1GaAs superlattices will be used to attempt to modify the sheath of edge states that appears in the quantum Hall regime. Signatures of the effects of the OOTF would appear in low-temperature magnetotransport experiments. Studies of chiral OOTF will investigate further their previously observed magnetic properties, when adsorbed onto Au; and whether the chiral QQTF retain their magnetic properties when adsorbed onto GaAs.