Ab initio study of Ga-GaN system: Transition from adsorbed metal atoms to a metal-semiconductor junction

Przemysław Witczak, Pawel Kempisty, Pawel Strak, Stanisław Krukowski

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5 Citations (Scopus)


Ab initio studies of a GaN(0001)-Ga system with various thicknesses of a metallic Ga layer were undertaken. The studied systems extend from a GaN(0001) surface with a fractional coverage of gallium atoms to a Ga-GaN metal-semiconductor (m-s) contact. Electronic properties of the system are simulated using density functional theory calculations for different doping of the bulk semiconductor. It is shown that during transition from a bare GaN(0001) surface to a m-s heterostructure, the Fermi level stays pinned at a Ga-broken bond highly dispersive surface state to Ga-Ga states at the m-s interface. Adsorption of gallium leads to an energy gain of about 4 eV for a clean GaN(0001) surface and the energy decreases to 3.2 eV for a thickly Ga-covered surface. The transition to the m-s interface is observed. For a thick Ga overlayer such interface corresponds to a Schottky contact with a barrier equal to 0.9 and 0.6 eV for n- and p-type, respectively. Bond polarization-related dipole layer occurring due to an electron transfer to the metal leads to a potential energy jump of 1.5 eV, independent on the semiconductor doping. Additionally high electron density in the Ga-Ga bond region leads to an energy barrier about 1.2 eV high and 4 Å wide. This feature may adversely affect the conductivity of the n-type m-s system.

Original languageEnglish
Article number061101
JournalJournal of Vacuum Science and Technology A: Vacuum, Surfaces and Films
Issue number6
Publication statusPublished - Nov 1 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films


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