| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
|
| Symposium
|
2011 Electronic Materials Conference
|
| Presentation Title |
DD5, Fe3O4/GaAs Hybrid Ferromagnet/Semiconductor Nanostructures |
| Author(s) |
Paul M. Riechers, Jun Chen, Christopher B. Murray, Richard A. Kiehl |
| On-Site Speaker (Planned) |
Paul M. Riechers |
| Abstract Scope |
A technology for creating hybrid ferromagnet/semiconductor nanostructures could enable the development of ultra-high-density non-volatile memories, low-power spintronic logic circuitry, and powerful quantum computing systems. The magnetic interaction between the two materials is the key that can open a door to electrical control of spin states, which could be highly exploited for design flexibility and device scalability. The injection of electrons into GaAs through ferromagnetic contacts could provide the spin-polarized current needed for various spintronic transistor, memory and logic proposals [1]. The modification of electron spin dynamics in GaAs by adjacent ferromagnetic regions via ferromagnetic proximity polarization [2] could allow control of the quantum states of selected electron spins, as needed for quantum computing. Ultimately these hybrid structures must reach nanometer scale dimensions in order to exploit single domains and superparamagnetic properties and to allow ultimate scaling of circuitry. The nanoscale could be reached by using a bottom-up approach like DNA scaffolding [3] to self-assemble ferromagnetic nanoparticles into precise geometries. However, the assembly of nanostructures from solution introduces serious problems for attaining high-quality interfaces with suitable mechanical and electronic properties due to unwanted oxides and organics created during the process. Here we report a technique for bonding self-assembled arrays of oleic acid-coated Fe3O4 nanoparticles to a GaAs substrate, a technologically important pair of materials. Our protocol involves separate oxide and organic removal steps together with an optimized thermal annealing cycle. SEM and AFM images provide dramatic topographical evidence for strong bonding between the two materials. Solution phase synthesized 20-nm Fe3O4 nanoparticles suspended in hexane [4] were drop cast or adsorbed onto a (100) GaAs surface precleaned in NH4OH. The samples were then exposed to a gentle oxygen plasma step to remove organics and subjected to various rapid thermal annealing cycles in the range of 200 to 400 °C. The integrity of the adhesion between the nanoparticles and surface was evaluated by scraping the edge of a glass slide across the substrate and performing comparative analysis of the interface by SEM and AFM. Certain combinations of precleaning, oxygen plasma treatment and thermal annealing parameters were found to produce SEM images consistent with strong bonding between the nanoparticles and the substrate. Topographical AFM images add convincing evidence for a physical restructuring or intermixing at the interface. Further study will be needed to evaluate the chemical and electronic nature of the interface in these and other hybrid ferromagnet/semiconductor nanostructures. We believe that the techniques described here will be highly valuable for future studies. |
| Proceedings Inclusion? |
Undecided |