We investigated carrier localization in basal-plane stacking faults (BPSF) in Si-doped nonpolar a-plane GaN (a-GaN) epilayers containing various BPSF densities. Different SiNx interlayers were used to control the BPSF density in the a-GaN films. Significantly reduced BPSF densities were realized by the insertion of thick SiNx and multi-SiNx/GaN interlayers. BPSF-related emissions in low-temperature photoluminescence (PL) spectra showed the smallest full width at half maximum (25 meV), as well as predominant near-band-edge emission peaks for samples with multi-SiNx/GaN interlayers. The role of BPSFs as carrier/exciton localization centers was confirmed from the S-shaped temperature dependence of the BPSF peak energies. Moreover, carrier localization energies, extracted from the S-shaped curve fitted to Varshni's formula, were determined not to be solely dependent on BPSF density. It is suggested that localization energy can be influenced by other factors such as donors in the vicinity of a BPSF or polarization-induced electric fields. Carrier localization energies within BPSFs were in good agreement with the low-temperature activation energies from Arrhenius plots of integrated PL intensity. Stronger carrier localization within BPSFs can be realized when a-GaN epilayers contain multi-SiNx/GaN interlayers.
Bibliographical noteFunding Information:
The authors gratefully acknowledge support from the Seoul RandBD Program (WR080951) and the Brain Korea 21 Plus Project in 2014 from Korea University. This present research was also supported by 2015 Hongik University Research Fund and the Basic Science Research Programs through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2014R1A1A4A01008877).
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- Basal-plane stacking fault
- Carrier localization
ASJC Scopus subject areas
- Biomedical Engineering
- Materials Science(all)
- Condensed Matter Physics