AVS 58th Annual International Symposium and Exhibition
    Electronic Materials and Processing Division Monday Sessions
       Session EM1-MoA

Paper EM1-MoA10
Quantum Dot Transfer using Patterned Self-Assembled Monolayers

Monday, October 31, 2011, 5:00 pm, Room 209

Session: Group III-Nitrides and Hybrid Devices
Presenter: Shawn Miller, University of Arizona
Authors: S. Miller, University of Arizona
A.J. Muscat, University of Arizona
Correspondent: Click to Email
Nano particles such as light emitting quantum dots offer many exiting new possibilities for device manufacturing. Along with the potential for low cost manufacturing, the ability to make quantum dot based solar cells and LEDs, has lead to the potential to make arrays of light detectors and nanometer scale patterned LEDs. Using two such devices together results in an optical switch, which may be employed in computer processing as a fast memory readout device. In addition ROM memories can be created using direct patterning of light emitting quantum dots on a disk. Because quantum dots of different size emit different wavelengths it is possible to code data in several wavelengths allowing the data from each wavelength to be written in the size limited area of focused light, dramatically increasing data storage. Many of the potential devices which can be made using nano particles require precise control over nano particle placement and layer thickness. We have found that it is possible to control quantum dot placement using a patterned self-assembled monolayer (SAM). Due to the hydrophobic properties of octadecyltrichlorosilane (OTS) it is possible to form an OTS SAM on which quantum dots will not deposit. This SAM layer can then be patterned using one of several methods. One approach is to use direct UV light exposure in air through a shadow mask, this will remove the OTS SAM in the open areas of the mask, allowing for quantum dot deposition to occur only in the open areas. OTS SAMs can also be formed on pre-made chemical patterns. Ultra high resolution patterns can be formed using nano-lithography including conductive atomic force microscopy, STM, and EBL. Arrays of conductive atomic force microscope tips can be used to pattern repeated patterns such as those required for detectors. Quantum dots or an alternate SAM can then be deposited directly into the open pattern areas. However, because of the time required for nano-lithography, it is desirable to use the patterned OTS SAM as a nano particle master stamp, where the quantum dots are transferred from the patterned OTS surface to a surface which chemically binds them. A self-assembled monolayer such as APTMS can be used to bind the quantum dots and remove them from the master patterned stamp, allowing the patterned OTS SAM to be repeatedly filled with quantum dots and stamped. This has been demonstrated using CdTe quantum dots with TGA ligands; however, there are a variety of nano particles with which this technique will work. Therefore by creating a patterned SAM and utilizing selective deposition and appropriate transfer chemistry it is possible to open a new realm of potential device manufacturing.