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HL: Fachverband Halbleiterphysik

HL 11: Focused Session: Semi- and nonpolar group III nitrides I

HL 11.1: Topical Talk

Dienstag, 24. März 2009, 09:30–10:00, HSZ 01

Characterization and Control of Recombination Dynamics in Low-dimensional InGaN-based Semiconductors — •Yoichi Kawakami, Akio Kaneta, Masaya Ueda, and Mitsuru Funato — Department of Electronic Science and Engineering, Kyoto University, Kyoto 615-8510, Japan

We have recently proposed the re-growth technique, where c-oriented (0001) GaN is used as a seed, where the growth on GaN templates patterned with a striped geometry along the [1-100] direction form (0001), <11-22>, and <11-20> facets. We found that the InGaN/GaN QWs on the <11-22> semipolar facets show higher photoluminescence (PL) efficiency, compared with conventional (0001) QWs. Consequently, nanoscopic optical characterization was performed on <11-22> microfacet QWs using scanning near field optical microscopy (SNOM). Unlike the phenomena observed in (0001) QWs, there is not a difference between the PL spectra acquired under the illumination-collection and illumination modes, which indicates that the carrier diffusion length in the <11-22> QW is less than the probing fiber aperture of 160 nm due to a much faster radiative recombination processes as a result of a well-reduction of internal electric field. The correlation between IQE and emission wavelength shows that the highest internal quantum efficiency (IQE) is approximately 50% at 520 nm, which is about 50 nm longer than in (0001) QWs, suggesting that the <11-22> QW is a suitable green emitter with a controllability of polarization direction. Moreover, tailored emission color synthesis has been achieved using the combination of microfacet QWs without phosphors.