Atomic and electronic structure of AlN polar surfaces

ORAL

Abstract

We studied the stability and electronic structure of AlN (0001) and (000-1) polar surfaces using first-principles DFT methods. A plane-wave basis set and PAW potentials are employed surface calculations. ~In order to correct the band gap of AlN, we applied the hybrid functional in the HSE [1] framework. ~Using this approach, we obtained a band gap of 6.1 eV, and lattice constants in excellent agreement with experimental values. Under Al-rich conditions, the Al adatom at T4 sites on the Al-terminated (0001) surface was found to be the most stable (2x2) reconstruction.~ This reconstruction is characterized by occupied surface states (Al-Al bonding) at 3.0 eV below the conduction-band minimum (CBM) and unoccupied surface states (Al dangling bonds) at 1.1 eV below the CBM. ~Under Al-poor conditions, the N adatom at the H3 site is the most stable reconstruction, with occupied N-Al bonding states at 4.2 eV and an uncoccupied Al dangling-bond state at 1.1 eV below the CBM.~ For the N-terminated (000-1) polar surface, the structure with an Al adlayer is the most stable under Al-rich conditions. ~The impact of the surface states on the properties of materials and devices will be discussed. [1] J. Heyd, G.E.Scuseria, and M.Ernzerhof, J. Chem. Phys. 118, 8207(2003).

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Authors

  • Maosheng Miao

    Materials Department, University of California, Santa Barbara

  • Anderson Janotti

    Materials Department, University of California, Santa Barbara, University of California, Santa Barbara, Materials Department, University of California at Santa Barbara, Materials Department, University of California, Santa Barbara, CA 93106-5050, University of California - Santa Barbara

  • Chris Van de Walle

    Materials Department, University of California, Santa Barbara, CA 93106-5050, Materials Department, University of California, Santa Barbara, University of California, Santa Barbara, Materials Department, University of California Santa Barbara, UCSB, Chris Van de Walle, University of California, Santa Barbara, Materials Department, University of California at Santa Barbara