Low dislocation density GaN grown by MOCVD with SiNx nano-network

J. Xie; Ü. Özgür; Y. Fu; X. Ni; H. Morkoç; C. K. Inoki; T. S. Kuan; J. V. Foreman; H. O. Everitt

doi:10.1117/12.706936

8 February 2007 Low dislocation density GaN grown by MOCVD with SiN_x nano-network

J. Xie, Ü. Özgür, Y. Fu, X. Ni, H. Morkoç, C. K. Inoki, T. S. Kuan, J. V. Foreman, H. O. Everitt

Proceedings Volume 6473, Gallium Nitride Materials and Devices II; 647304 (2007) https://doi.org/10.1117/12.706936
Event: Integrated Optoelectronic Devices 2007, 2007, San Jose, California, United States

Abstract

GaN epitaxial layers grown on SiC and sapphire suffer from high density of line and point defects. To address this problem, new growth methods using in situ or ex situ nano-network masks as dislocation filters have been introduced recently. In this work, we report on metalorganic chemical vapor deposition (MOCVD) of GaN layers on 2-inch sapphire substrates using in situ SiN_x nano-networks intended for defect reduction. SiN_x interlayers with different deposition times were employed after ~2 &mgr;m GaN grown on sapphire, which was followed by ~3.5 &mgr;m GaN overgrowth. With increasing SiN_x coverage, full width at hall maximum (FWHM) values of (0002) and (10₁^-2) X-Ray diffraction (XRD) peaks monotonously decrease from 252 arc sec to 217 arc sec and from 405 ar csec to 211 arc sec, respectively for a 5.5 &mgr;m thick film. Similarly, transmission electron microscopy (TEM) revealed that screw and edge type dislocation densities as low as 4.4x10⁷ cm^-2 and 1.7x10⁷ cm^-2 were achieved. The use of SiN_x nanonetwork also increases the radiative recombination lifetimes measured by time-resolved photoluminescence to 2.5 ns from less than 0.5 ns in control GaN. We have also fabricated Ni/Au Schottky diodes on the overgrown GaN layers and the diode performance was found to depend critically on SiN_x coverage, consistent with TEM, XRD and TRPL results. A 1.13eV barrier height was achieved when SiN_x layer was used compared to 0.78 eV without any SiN_x nanonetwork. Furthermore, the breakdown voltage was improved from 76 V to 250 V with SiN_x nanonetwork.

Citation Download Citation

J. Xie, Ü. Özgür, Y. Fu, X. Ni, H. Morkoç, C. K. Inoki, T. S. Kuan, J. V. Foreman, and H. O. Everitt "Low dislocation density GaN grown by MOCVD with SiN_x nano-network", Proc. SPIE 6473, Gallium Nitride Materials and Devices II, 647304 (8 February 2007); https://doi.org/10.1117/12.706936

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