AVS 66th International Symposium & Exhibition
    Electronic Materials and Photonics Division Thursday Sessions
       Session EM-ThP

Paper EM-ThP13
Examining the Compositional Uniformity of GaAsNBi Alloys using Atom Probe Tomography

Thursday, October 24, 2019, 6:30 pm, Room Union Station B

Session: Electronic Materials and Photonics Poster Session
Presenter: Jared W. Mitchell, University of Michigan, Ann Arbor
Authors: J.W. Mitchell, University of Michigan, Ann Arbor
C.M. Greenhill, University of Michigan, Ann Arbor
T.Y. Jen, University of Michigan, Ann Arbor
R.S. Goldman, University of Michigan, Ann Arbor
Correspondent: Click to Email
Due to the significant bandgap narrowing and complementary strain induced by dilute fractions of N and Bi in III-V semiconductors, dilute nitride-bismide alloys are of significant interest for near- and mid-infrared applications ranging from temperature-insensitive laser diodes to ultra-high efficiency multi-junction photovoltaic cells. However, to date, few dilute nitride-bismide compositions have been accessed experimentally, and determinations of alloy compositions have typically not accounted for the presence of interstitial N. Using direct measurements of N and Bi mole fractions, via ion beam analysis, in conjunction with direct measurements of the out-of-plane misfit via x-ray rocking curves, we recently determined the "magic ratio" for lattice-matching of GaAsNBi alloys with GaAs substrates.1 In addition, using photoreflectance and photoluminescence (PL) spectroscopy, we mapped the composition- and misfit-dependence of the bandgap energies. However, the PL emission from the layers displays an extended low-energy tail, likely due to emission from a distribution of localized states. To explore the origins of the localized states, we are examining alloy non-uniformities in GaAsNBi epilayers using local-electrode atom-probe (LEAP) tomography. In particular, we are exploring the role of N interstitial complexes and metallic cluster formation on the isovalent co-alloying of GaAs with Bi and N. We will present LEAP analysis of a series of nearly-lattice-matched GaAsNBi layers with various N and Bi fractions. We will also discuss correlations between alloy non-uniformities and local electronic states in GaAsNBi epilayers and heterostructures.

1. J. Occena, T. Jen, J.W. Mitchell, W.M. Linhart, E.-M. Pavelescu, R. Kudrawiec, Y.Q. Wang, and R.S. Goldman, Appl. Phys. Lett. in press (2019).