CuxBi2Se3 has drawn much attention as the leading candidate to be the first topological superconductor and the realization of coveted Majorana particles in a condensed matter system. However, there has been increasing controversy about the nature of its superconducting phase. This study sheds light on ambiguity in the normal-state electronic state by providing a complete look at the quantum oscillations in magnetization in CuxBi2Se3 at high magnetic fields up to 31 T. Our study focuses on the angular dependence of the quantum oscillation pattern in a low carrier concentration. As the magnetic field tilts from the crystalline c-axis to the ab-plane, the change of the oscillation period follows the prediction of the ellipsoidal Fermi surface. As the doping level changes, the 3D Fermi surface becomes quasi-cylindrical at high carrier density. Such a transition is potentially a Lifshitz transition of the electronic state in CuxBi2Se3.

Oxygen incorporation into ZnTe was studied using pulsed laser deposition and molecular beam epitaxy. Oxygen incorporation at the high partial pressures studied for pulsed laser deposition was found to result in increasing visible transparency with oxygen incorporation, and is attributed to the formation of TeO x based on bonding information obtained by x-ray photoelectron spectroscopy measurements. Oxygen incorporation by a plasma source during the growth of ZnTe by molecular beam epitaxy was found to result in an electronic band at 0.5 eV below the ZnTe band edge, possessing strong radiative properties and a resonant-like optical absorption coefficient with a peak a > 5000 cm -1 . The ZnTeO thin films grown by MBE have an epitaxial structure similar to ZnTe, where it is unclear whether the properties are due to the formation of a high-density defect level or the formation of a dilute alloy.

The LUX-ZEPLIN dark matter search aims to achieve a sensitivity to the WIMP-nucleon spinindependent cross-section down to (1-2)×10 −12 pb at a WIMP mass of 40 GeV/c 2. This paper describes the simulations framework that, along with radioactivity measurements, was used to support this projection, and also to provide mock data for validating reconstruction and analysis software. Of particular note are the event generators, which allow us to model the background radiation, and the detector response physics used in the production of raw signals, which can be converted into digitized waveforms similar to data from the operational detector. Inclusion of the detector response allows us to process simulated data using the same analysis routines as developed to process the experimental data.

Heterojunction diodes consisting of n-type ZnO and p-type ZnTe were grown by pulsed laser deposition and molecular beam epitaxy, respectively, on GaAs (001) substrates. Strong diode rectifying behavior was observed in the current-voltage characteristics with a current on/off ratio of J on /J off = 1 · 10 5 and a diode ideality factor of n = 1.5. A strong photoresponse in the energy range of 2.3 eV to 3.6 eV was observed, corresponding to the bandgap energies of ZnTe and ZnO, respectively. A photovoltaic response was observed with a relatively small fill factor with a short-circuit current J sc $ 0.8 mA/cm 2 and open-circuit voltage of V oc $ 60 mV subject to illumination by a tungsten lamp. The photovoltaic response and reverse saturation current are believed to be limited by defects related to the mismatch between the ZnTe and ZnO structures and defects in the ZnO layer deposited at low temperature. The spectral response of the diodes is modeled with a close match to experimental measurements.

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