AVS 60th International Symposium and Exhibition
    Atom Probe Tomography Focus Topic Wednesday Sessions
       Session AP+AS+EM+MI+TF-WeM

Invited Paper AP+AS+EM+MI+TF-WeM2
APT Analysis of Superlattices, Nanowires, and Non-Planar Heterostructures

Wednesday, October 30, 2013, 8:20 am, Room 203 A

Session: APT Analysis of Semiconductor, Magnetic, and Oxide Materials
Presenter: L.J. Lauhon, Northwestern University
Correspondent: Click to Email
I will describe pulsed laser atom probe tomography of semiconductors and semiconductor heterostructures in which the specimen or device geometry significantly limits the application of alternative analytical characterization techniques, thereby presenting unique opportunities for APT analysis. At the same time, geometry and other factors can complicate specimen preparation and APT interpretation. The talk will present both new scientific findings enabled by APT as well as challenges in data analysis, using three examples. First, I will describe the dopant distribution in semiconductor nanowires, for which APT studies have provided new understanding of dopant incorporation mechanisms. Additionally, advances in nanowire growth and design have enabled imaging of the entire nanowire diameter. Second, I will describe the analysis of InGaN/GaN superlattices extracted from light emitting diodes, for which APT is uniquely able to investigate fluctuations in indium mole fraction and the 3-D morphology of the InGaN quantum wells. In both GaN nanowires and thin-films, we have found that the surface polarity strongly influences the measured stoichiometry, but the indium mole fraction can be determined reliably. Finally, we have analyzed InGaN quantum wells grown on GaN nanowires. These are nonplanar heterostructures in which quantum wells are grown simultaneously on both polar and non-polar surfaces. Data from scanning transmission electron microscopy-based analytical methods will be compared with APT analysis, and the relative merits described. A comparison of these 3 examples will provide insights into the influence of intrinsic materials properties as well as specimen geometry on the capabilities and limitations of APT.