Ab initio-Based Approach to N-pair Formation on GaAs(001)-(2×4) Surfaces

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Author(s)

    • Ito Tomonori
    • Department of Physics Engineering, Graduate School of Engineering, Mie University, Japan
    • Sugitani Tatsuhiko
    • Department of Physics Engineering, Graduate School of Engineering, Mie University, Japan
    • Akiyama Toru
    • Department of Physics Engineering, Graduate School of Engineering, Mie University, Japan
    • Nakamura Kohji
    • Department of Physics Engineering, Graduate School of Engineering, Mie University, Japan

Abstract

Nitrogen-pair formation processes on the GaAs(001)-(2×4) surfaces found experimentally are systematically investigated using ab initio-based approach incorporating beam equivalent pressure <i>p</i> (<i>p</i><sub>A</sub><sub>s</sub> = 3.0 × 10<sup>-6</sup> Torr, <i>p</i><sub>N</sub> = 7.0 × 10<sup>-6</sup> Torr) and temperature <i>T</i> = 830 K. The calculated surface phase diagrams elucidates that the (2×4)α1 and (2×4)α2 surfaces are stable at the growth conditions under As<sub>2</sub> and As<sub>4</sub>, respectively. The Monte Carlo simulations reveal that the N incorporation on the (2×4)α1 and (2×4)α2 surfaces proceeds with increase of energetically favorable Ga-N bonds in the third layer via series of events such as adsorption of N-As dimer, substitution of N for As located in the third layer, and As dimer desorption to form the N-pair in the third layer. It is also found that the probability of the N-pair formation on the (2×4)α1 surface is much larger than that on the (2×4)α2 surface. This is because the strain around the N-pair on the (2×4)α1 surface is smaller than that on the (2×4)α2 surface where N-As surface dimer is formed to relax the larger strain. Furthermore, the N-pair formation probabilities <i>P</i> under As<sub>2</sub> and As<sub>4</sub> are estimated as a function of temperature including (2×4)β1. N atoms incorporated on the GaAs(001) surface can form N-pair along [110] with <i>P</i> ∼ 0.8 on the surface with two phase mixture of (2×4)α1 and (2×4)α2 at <i>T</i> = 830 K under As<sub>2</sub> and As<sub>4</sub>. [DOI: 10.1380/ejssnt.2014.6]

Journal

  • e-Journal of Surface Science and Nanotechnology

    e-Journal of Surface Science and Nanotechnology 12(0), 6-10, 2014

    The Surface Science Society of Japan

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