Optical studies on a coherent InGaN/GaN layer

abstract

Photoluminescence (PL), photoluminescence excitation (PLE) and selective excitation (SE-PL) studies were performed in an attempt to identify the origin of the emission bands in a pseudomorphic In0.05Ga0.95N/GaN film. Besides the InGaN near-band-edge PL emission centred at 3.25 eV an additional blue band centred at 2.74 eV was observed. The lower energy PL peak is characterized by an energy separation between absorption and emission - the Stokes' shift-(similar to 500 meV) much larger than expected. A systematic PLE and selective excitation analysis has shown that the PL peak at 2.74 eV is related to an absorption band observed below the InGaN band gap. We propose the blue emission and its related absorption band are associated to defect levels, which can be formed inside either the InGaN or GaN band gap. (c) 2006 Elsevier Ltd. All rights reserved.

keywords

YELLOW LUMINESCENCE; GAN; TRANSITIONS; EPILAYERS; EPITAXY; ORIGIN; STATES; DEEP; BAND

subject category

Physics

authors

Correia, MR; Pereira, S; Alves, E; Arnaudov, B

our authors

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