Domain Matching Epitaxy of Mg-Containing Ag Contact on p-Type GaN

• Published in: Crystal growth & design 2011-06, Vol.11 (6), p.2559-2563
• Main Authors: Song, Yang Hee, Son, Jun Ho, Yu, Hak Ki, Lee, Ju Ho, Jung, Gwan Ho, Lee, Jeong Yong, Lee, Jong-Lam
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg200323h

We present the epitaxial growth of Mg-containing Ag film on p-type GaN using domain matching epitaxy. No epitaxial growth was found in the as-deposited Ag film, but it changed to epitaxial growth as Mg atoms were added into Ag film. This is due to the fact that Mg atoms were preferentially bonded to O ones, which played a role in shrinking the surrounded Ag lattice from 4.0871 to 4.0858. In addition to that, the volume expansion induced by Mg–O chemical bonding moves the Ag atoms to the site where they are energetically most stable at the Ag/GaN interface, resulting in strong adhesion between Ag films and GaN substrate. As a result, nine domains of the (111)-oriented Ag layer (2.558 nm) are matched with eight domains of the (0001) GaN layer (2.551 nm). This arrangement has the lowest domain mismatch of 8.9%, resulting in the epitaxial growth of the (111) Ag film with the lowest surface energy. Consequently, the Mg-containing Ag film shows better thermal stability, resulting in the suppression of Ag agglomeration.