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Potential Barrier Formed Around Dislocations in InGaN Quantum Well Structures by Spot Cathodoluminescence Measurements
Author(s) -
Kurai Satoshi,
Higaki Shota,
Imura Nobuto,
Okawa Kohei,
Makio Ryoga,
Okada Narihito,
Tadatomo Kazuyuki,
Yamada Yoichi
Publication year - 2018
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700358
Subject(s) - cathodoluminescence , materials science , scanning electron microscope , photoluminescence , quantum well , spectral line , molecular physics , analytical chemistry (journal) , luminescence , optics , optoelectronics , chemistry , laser , physics , composite material , chromatography , astronomy
We carried out spot cathodoluminescence (CL) with scanning electron microscopy (SEM‐CL) of InGaN multiple quantum well (MQW) structures with an In molar fraction of 18% grown on c‐plane sapphire at room temperature, in which formation of a potential barrier around threading dislocations was confirmed in previous spatially resolved photoluminescence measurements with scanning near‐field optical microscopy (SNOM‐PL). We confirmed the suitability of CL measurements for evaluating the local potential barriers near the dislocations. Local emissions around the V‐pits were observed in monochromatic CL mapping images acquired at the higher‐energy side of InGaN emissions at RT and 78 K. The density of the higher‐energy emission regions was smaller than the V‐pit density, indicating the effect of nonradiative recombination. Spot CL spectra around the V‐pits showed shoulders on the higher‐energy side of the InGaN peaks. These observations agree with the SNOM‐PL results acquired from the same samples, indicating that SEM‐CL can be used to evaluate potential barriers. The emission energy difference between the InGaN and higher‐energy emissions estimated by spot CL spectra was compared with that estimated by SNOM‐PL spectra. The energy difference as a function of pit diameter showed a similar trend for both measurement methods, but was slightly smaller for the SEM‐CL results, suggesting that the potential barrier height evaluation is not necessarily quantitative.