Spatial Inhomogeneity of Photoluminescence in InGaN Single Quantum Well Structures

Abstract

Spatial distribution of photoluminescence (PL) spectra has been assessed in an InGaN single quantum well (SQW) structure by means of fluorescence microscopy and scanning near-field optical microscopy (SNOM) under illumination-collection mode. The PL intensity of fluorescence image is uniform at 77 K, but the dark spot areas were extended with increasing temperature. The nearfield PL images revealed the variation of both peak energy and intensity in PL spectra according to the probing location with the scale less than a few hundreds nm. phys. stat. sol. (b) 228, No. 1, 153-156 (2001) # WILEY-

Spatial and temporal luminescence dynamics in an InxGa1−xN single quantum well probed by near-field optical microscopy

“…5,6 Several reports have recently been appeared on the spatial mapping of luminescence in In x Ga 1Ϫx N single-quantum wells ͑SQWs͒ by cathodoluminescence, [7][8][9] or by photoluminescence ͑PL͒ using scanning-near field optical microscopy ͑SNOM͒. [10][11][12][13][14][15][16][17][18] Most of the SNOM results were obtained using an illumination-mode system, which is very difficult to know whether excitons and/or carriers producing PL are directly photogenerated at the probe region or they are diffused from outside. This problem can be overcome by means of an illumination-collection mode 19 developed recently for the assessment of wide gap semiconductors.…”

“…This problem can be overcome by means of an illumination-collection mode 19 developed recently for the assessment of wide gap semiconductors. 15,16 In this letter, the spatial inhomogeneiety and the temporal dynamics have been assessed at 18 K in a blue emitting In x Ga 1Ϫx N SQW by employing SNOM-PL and SNOMtime-resolved PL ͑TRPL͒ under the illumination-collection mode.…”

Optical Characterization of InGaN Quantum Structures at the Nanoscale

“…Thanks to its capacity to extend optical characterization into the nanoscale resolution realm, there have been numerous reports of spatial inhomogeneity in emission. [17][18][19][20][21] These irregularities are typically attributed to dislocations and fluctuations in Indium composition. As for the former, early work by A. Vertikov et al [22] suggested that strong carrier localisation in InGaN alloys might mitigate the adverse effects of dislocation on PL efficiency.…”