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Proceedings Paper

Characterization of GaN layers by second harmonic generation and photoluminescence
Author(s): Saulius Juodkazis; Augustinas Galeckas; Juozas V. Vaitkus; Shiro Sakai; Hiroaki Misawa
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Paper Abstract

We have observed an apparent rotational anisotropy of the second harmonic generation (SHG) at signal at (lambda) = 405 nm back-reflected from the surface (0001) of 3 micrometers -thick GaN grown by metalorganic chemical vapor deposition (MOCVD). The focusing depth of 2 micrometers was aimed to probe the 10-15 nm-thick buffer layer where both cubic and hexagonal phases of GaN are coexisting. Typical angular dependency clearly indicated the presence of both isotropic and six-fold contributions. The isotropic I(2(omega ))(qq) component has a minor one-fold modulation due to a ca. 2 degree(s) disorientation of the top surface with respect to the hexagonal planes. We attribute the substantial isotropic component to the SHG yield from the bulk of GaN. The occurrence of six-fold I(2(omega )) (qq) anisotropy, however, indicates a complementary nonlinearities, most likely due to hexagonal phase, which is coexisting with the hexagonal one in the buffer layer region. In general, both surface and bulk nonlinearities are contributing to the reflected SH yield. The symmetry of surface can differ from that in the bulk, exhibiting a corresponding angular dependence of harmonic generation. SHG mapping of GaN (ooo1) surface was measured from the ablated pattern. Space-Time-Spectra resolved photoluminescence (PL) was used to characterize the InGaN layers and GaN/InGaN MQW laser structures. Two-photon absorption (TPA) excited mapping of the dislocation network in GaN layers is demonstrated.

Paper Details

Date Published: 8 March 2001
PDF: 6 pages
Proc. SPIE 4318, Smart Optical Inorganic Structures and Devices, (8 March 2001); doi: 10.1117/12.417588
Show Author Affiliations
Saulius Juodkazis, Vilnius Univ. (Japan)
Augustinas Galeckas, Vilnius Univ. (Sweden)
Juozas V. Vaitkus, Vilnius Univ. (Lithuania)
Shiro Sakai, Univ. of Tokushima (Japan)
Hiroaki Misawa, Univ. of Tokushima (Japan)

Published in SPIE Proceedings Vol. 4318:
Smart Optical Inorganic Structures and Devices
Steponas P. Asmontas; Jonas Gradauskas, Editor(s)

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