Dislocation distribution and subgrain structure of GaN films deposited on sapphire by HVPE and MOVPE

K. A. Dunn, S. E. Babcock, R. Vaudo, V. Phanse, J. Redwing

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


Transmission electron microscopy (TEM) was used to characterize the microstructure in GaN films deposited by two different methods. An 11 μm thick film was deposited directly on a sapphire substrate by HVPE; an 8 μm thick film was deposited on a 15 nm buffer layer of AlN on sapphire by MOVPE. The dislocation densities in the top layer of the HVPE and MOVPE films were approximately 109 cm-2 and approximately 5×109 cm-2 respectively. In the HVPE film this was almost exclusively threading dislocations (TDs), approximately 70% of which had edge character. In addition to the TDs, the MOVPE sample also contained an appreciable number of dislocations lying in the basal plane. The microstructure of each film was dominated by a subgrain structure of slightly misoriented cells. In the MOVPE specimen, approximately 90% of the TDs were associated with subgrain walls, whereas only approximately 75% of the dislocations in the HVPE specimen were associated with walls. Both the HVPE and MOVPE samples experienced 40% coarsening of the cells through the thickness of the film. The subgrains of the MOVPE sample were 75% smaller than those in the HVPE sample (350 and 1300 nm, respectively). The average dislocation spacing in the walls was 50% smaller in the MOVPE sample than in the HVPE sample (82 and 180 nm, respectively).

Original languageEnglish (US)
Pages (from-to)417-422
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
StatePublished - Jan 1 1997
EventProceedings of the 1997 MRS Fall Meeting - Boston, MA, USA
Duration: Dec 1 1997Dec 4 1997

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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