Characterization of GaN epitaxial films grown on SiN<sub>x</sub> and TiN<sub>x</sub> porous network templates

J. Xie; Y. Fu; Ü. Özgür; Y. T. Moon; F. Yun; H. Morko; H. O. Everitt; A. Sagar; R. M. Feenstra; C. K. Inoki; T. S. Kuan; L. Zhou; D. J. Smith

doi:10.1117/12.646858

3 March 2006 Characterization of GaN epitaxial films grown on SiN_x and TiN_x porous network templates

J. Xie, Y. Fu, Ü. Özgür, Y. T. Moon, F. Yun, H. Morko, H. O. Everitt, A. Sagar, R. M. Feenstra, C. K. Inoki, T. S. Kuan, L. Zhou, D. J. Smith

Author Affiliations +

Proceedings Volume 6121, Gallium Nitride Materials and Devices; 61210B (2006) https://doi.org/10.1117/12.646858
Event: Integrated Optoelectronic Devices 2006, 2006, San Jose, California, United States

Abstract

We report on the structural, electrical, and optical characterization of GaN epitaxial layers grown by metalorganic chemical vapor deposition (MOCVD) on SiN_x and TiN_x porous templates in order to reduce the density of extended defects. Observations by transmission electron microscopy (TEM) indicate an order of magnitude reduction in the dislocation density in GaN layers grown on TiN_x and SiN_x networks (down to ~10⁸ cm^-2) compared with the control GaN layers. Both SiN_x and TiN_x porous network structures are found to be effective in blocking the threading dislocation from penetrating into the upper layer. Supporting these findings are the results from X-Ray diffraction and low temperature photoluminescence (PL) measurements. The linewidth of the asymmetric X-Ray diffraction (XRD) (1012) peak decreases considerably for the layers grown with the use of SiN_x and TiN_x layers, which generally suggests the reduction of edge and mixed threading dislocations. In general, further improvement is observed with the addition of a second SiNx layer. The room temperature decay times obtained from biexponential fits to time-resolved photoluminescence (TRPL) data are increased with the inclusion of SiN_x and TiN_x layers. TRPL results suggest that primarily point-defect and impurity-related nonradiative centers are responsible for reducing the lifetime. The carrier lifetime of 1.86 ns measured for a TiN_x network sample is slightly longer than that for a 200 μm-thick high quality freestanding GaN. Results on samples grown by a new technique called crack-assisted lateral overgrowth, which combines in situ deposition of SiN_x mask and conventional lateral overgrowth, are also reported.

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J. Xie, Y. Fu, Ü. Özgür, Y. T. Moon, F. Yun, H. Morko, H. O. Everitt, A. Sagar, R. M. Feenstra, C. K. Inoki, T. S. Kuan, L. Zhou, and D. J. Smith "Characterization of GaN epitaxial films grown on SiN_x and TiN_x porous network templates", Proc. SPIE 6121, Gallium Nitride Materials and Devices, 61210B (3 March 2006); https://doi.org/10.1117/12.646858

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