Influence of nitrogen ion species on mass-selected low energy ion-assisted growth of epitaxial GaN thin films

Abstract

The application of an energy and mass selected ion beam assisted deposition setup to investigate the influence of hyperthermal atomic and molecular nitrogen ion species during the initial stages of epitaxial GaN thin film growth is reported. By using a compact quadrupole mass filter system a hyperthermal ion beam is mass filtered. The GaN thin film depositions with varying ion-to-atom arrival ratio and kinetic energies of 40 eV and 80 eV are performed to highlight the distinct impact of the ion species on the early stages of the growth. It is evaluated that precise selection of ion beam parameters enables the preferred growth of either the metastable zinc blende GaN phase or the stable wurtzite GaN phase on 6H-SiC(0001) substrates. Further, using molecular nitrogen ion species thin films of high crystalline quality could be deposited even at ion kinetic energies of 80 eV, while films with atomic nitrogen ion assistance feature reduced crystalline quality.