Study of interference effects on the photoluminescence of AlGaN/GaN quantum wells

• Published in: Physica status solidi. C Vol. 12; no. 4-5; pp. 365 - 368
• Main Authors: Ramírez-López, M., Casallas-Moreno, Y. L., Pérez-Caro, M., Escobosa-Echevarria, A., Gallardo-Hernández, S., Huerta-Ruelas, J., Lopez-Lopez, M.
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.04.2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Aluminum gallium nitrides; Beams (radiation); Buffer layers; Carrier density; Epitaxial growth; Gallium nitrides; GaN; Interference; modulated photoluminescence; Modulation; Molecular beam epitaxy; Optical properties; Oscillations; PAMBE; Photoluminescence; Quantum wells; Reflectance; Refractivity; Sapphire; Silicon substrates
• ISSN: 1862-6351; 1610-1642
• DOI: 10.1002/pssc.201400185

In this work we compared the optical properties of AlGaN(50 nm)/GaN(5 nm) quantum wells (QWs) grown by plasma‐assisted molecular beam epitaxy (PAMBE) technique, on Si(111) substrates and sapphire substrates. Optical properties were acquired by photoluminescence (PL) and reflectance (R) spectroscopies. Reflectance spectra shows interference oscillations of the reflected beam at Air/AlGaN and the beam reflected at bottom interface with Si substrate. Such oscillations vanish at the band gap of GaN buffer layer (3.4 eV). The PL spectra of samples grown on Silicon substrate shows a photoluminescence modulation effect, attributed to interference of light emitted from the QWs that is reflected at different heterostructure interfaces. On sapphire substrate no modulation effect is present. This could be explained due to interfacial roughness and the smaller refractive index of sapphire in comparison to silicon. PL shows a strong emission around 3 eV, which is in agreement with recombination energy determined by self‐consistent calculations, which consider a 4 MV/cm built‐in electric field and low carrier densities. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)