Correlation of spectral luminescence with threading dislocations in green-light-emitting InGaN quantum wells

Abstract

A direct correlation has been established between the spatial variation of spectral luminescence and the distribution of threading dislocations in a green-light-emitting InGaN quantum well structure grown on a sapphire substrate. Transmission electron microscopy and monochromatic cathodoluminescence images, taken from the same region, indicate that the nature of the quantum well emission is influenced by the microstructure of the underlying GaN. The microstructure is defined by threading dislocations that reflect a columnar structure with low-angle grain boundaries. A strong correlation is observed between this microstructure and the peak and low-energy portion of the quantum well luminescence, with threading dislocations as boundaries between bright and darker regions. The high-energy portion of the luminescence is localized and is generally complementary to the rest of the spectrum.

Factors affecting the luminescence emission of InGaN multi‐quantum wells grown on (0001) sapphire substrates by MOVPE

“…The size of these disks is a matter of controversy. Small InN rich clusters (nanometer size) are detected by TEM measurements [6], while CL experiments reveal the existence of lateral luminescence intensity fluctuations at a mesoscopic scale [5][6][7][8][9]. CL is a powerful characterization tool for these heterosctructures, since one can select the excitation depth, and one can acquire images of the emission patterns with a resolution adapted to the distribution range of In.…”

Spatially Resolved Cathodoluminescence in the Vicinity of Defects in the High-Efficiency InGaN/GaN Blue Light Emitting Diodes

“…In addition, from its spatially resolved luminescence profile, one can estimate a dislocation distribution inside the sample without destructing its structure. There have been numerous researches on using the CL measurements to examine the properties of the GaN as well as InGaN/GaN MQWs [13,14]. However, to the best of our knowledge, there have not been any reports on CL mapping of a high-efficiency InGaN/GaN blue LED structure with an additional high-energy emission.…”

Scanning near‐field luminescence microscopy of green light emitting GaInN/GaN quantum wells grown on c‐plane sapphire and on c‐plane bulk GaN

“…To clarify the influence of dislocations on the efficiency of green-emitting GaInN/GaN structures, it is necessary to investigate the spatial structure of the luminescence of such structures on a sub micrometer length scale. Possible methods for such experiments are microscopic photoluminescence (μPL) [8], cathodoluminescence (CL) [9] or scanning near-field optical microscopy (SNOM) [10]. In this work we will present SNOM measurements of green light emitting GaInN/GaN quantum well structures of identical well width and comparable indium content, which were grown on substrates, with different dislocation densities, conventional c-plane sapphire and commercial c-plane bulk GaN.…”