Structural defects in bulk GaN

• Published in: Journal of crystal growth Vol. 403; pp. 66 - 71
• Main Authors: Liliental-Weber, Z., dos Reis, R., Mancuso, M., Song, C.Y., Grzegory, I., Porowski, S., Bockowski, M.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2014; Elsevier
• Subjects: A1. Dislocations; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystal defects; Crystal perfection in HVPE layers grown on ammonothermal substrates; Defects and impurities in crystals; microstructure; Defects in high pressure grow layers; Density; Dislocations; Exact sciences and technology; Gallium nitrides; Linear defects: dislocations, disclinations; Magnesium; Materials science; Methods of crystal growth; physics of crystal growth; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Precipitates; Precipitation; Structure and morphology; thickness; Structure of solids and liquids; crystallography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation; Thin film structure and morphology; Transmission electron microscopy; Vapor phase epitaxy; growth from vapor phase; A1. Dislocations; Defects in high pressure grow layers; Precipitates; Crystal perfection in HVPE layers grown on ammonothermal substrates; Magnesium additions; Defect density; Crystal defects; Layered crystals; Thick films; Crystal seeds; VPE; Layer thickness; Crystal perfection; III-V compound; Dislocations; High pressure; Voids; Dislocation density; Transmission electron microscopy; Blood platelets; Growth mechanism; Chemical composition; III-V semiconductors
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2014.06.022

Transmission Electron Microscopy (TEM) studies of undoped and Mg doped GaN layers grown on the HVPE substrates by High Nitrogen Pressure Solution (HNPS) with the multi-feed-seed (MFS) configuration are shown. The propagation of dislocations from the HVPE substrate to the layer is observed. Due to the interaction between these dislocations in the thick layers much lower density of these defects is observed in the upper part of the HNPS layers. Amorphous Ga precipitates with attached voids pointing toward the growth direction are observed in the undoped layer. This is similar to the presence of Ga precipitates in high-pressure platelets, however the shape of these precipitates is different. The Mg doped layers do not show Ga precipitates, but MgO rectangular precipitates are formed, decorating the dislocations. Results of TEM studies of HVPE layers grown on Ammonothermal substrates are also presented. These layers have superior crystal quality in comparison to the HNPS layers, as far as density of dislocation is concern. Occasionally some small inclusions can be found, but their chemical composition was not yet determined. It is expected that growth of the HNPS layers on these substrate will lead to large layer thickness obtained in a short time and with high crystal perfection needed in devices. •The HVPE layers grown on Ammono thermal have superior crystal quality in comparison to the HNPSlayers.•Selective area diffraction pattern from these precipitates show the formation of the MgO precipitates•Long dislocations are not observed in the HVPE layers grown on the Ammono thermal substrates.