Open symbols: theory Closed symbols: experiment

1. Native point defects and doping of heterovalent ternary wide band gap semiconductorsWalter R. L. Lambrecht, Case Western Reserve University, DMR 1104595 A new family of semiconductor nitrides with general formula II-IV-N2, e.g. ZnGeN2 are being explored as opto-electronic materials. They are potentially easier to dope p-type because of the versatility of having two cations with different valence. Band gaps obtained within the quasiparticle self-consistent GW method are shown compared to those of the group III nitrides in the figure on the top. They span the red to ultraviolet region. The band dispersion near the valence band maximum (VBM) for ZnSnN2 shown as an example in the bottom figure is parametrized in terms of an effective Hamiltonian and forms the starting point for calculating shallow acceptor levels using the effective mass approximation. The splitting of the VBM in levels of different symmetry leads to anisotropic optical properties.The chemical potential stability region of ZnSnN2 is shown in the inset and will be used to determine the energies of formation of vacancies and antisite defects using first-principles calculations. Open symbols: theory Closed symbols: experiment Note the band gap In the green for CdGeN2

2. Fulbright award for PI for studies of point defects, student achievementsWalter R. L. Lambrecht, Case Western Reserve University, DMR 1104595 The PI received a Fulbright grant to collaborate with scientists at the Peter Grünberg Institute of the Forschungszentrum Jülich, Germany on the development of improved methods for calculating point defects in semiconductors. He spends a sabbatical there in summer/fall 2012. Graduate student Atchara Punya published a paper on effective Hamiltonians in nitrides and co-authors a book chapter on II-IV-N2 semiconductors. Graduate student Tawinan Cheiwchanchamnangij published a paper on excitons in MoS2 monolayers and collaborated on a paper on wurtzite GaAs nanowires. Undergraduate student Jacob Emmert Aronson developed effective mass approximation calculations and presented his results at APS March meeting. He is now pursuing a Ph.D. at UC Berkeley. Jacob Tawinan Atchara