Manganese 3x3 and root 3 x root 3-R30 degrees structures and structural phase transition on omega-GaN(000(1)over-bar) studied by scanning tunneling microscopy and first-principles theory

Article

关键词: EPITAXIAL-GROWTH;    FE;    PSEUDOPOTENTIALS;    RECONSTRUCTIONS;    GAN(0001);    ENERGY;   

DOI  :  10.1103/PhysRevB.87.165426

来源: SCIE

【 摘 要 】

Manganese deposited on the N-polar face of wurtzite gallium nitride [GaN (000 (1) over bar)] results in two unique surface reconstructions, depending on the deposition temperature. At lower temperature (less than 105 degrees C), it is found that a metastable 3 x 3 structure forms. Mild annealing of this Mn 3 x 3 structure leads to an irreversible phase transition to a different, much more stable root 3 x root 3-R30 degrees structure which can withstand high-temperature annealing. Scanning tunneling microscopy (STM) and reflection high-energy electron diffraction data are compared with results from first-principles theoretical calculations. Theory finds a lowest-energy model for the 3 x 3 structure consisting of Mn trimers bonded to the Ga adlayer atoms but not with N atoms. The lowest-energy model for the more stable root 3 x root 3-R30 degrees structure involves Mn atoms substituting for Ga within the Ga adlayer and thus bonding with N atoms. Tersoff-Hamman simulations of the resulting lowest-energy structural models are found to be in very good agreement with the experimental STM images. DOI: 10.1103/PhysRevB.87.165426

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