Time-resolved photoluminescence and photoreflectance spectroscopy of GaN layers grown on SiN-treated sapphire substrate: Optical properties evolution at different growth stages

Correlation of structural and optical properties of AlGaN films grown on SiN-treated sapphire by MOVPE

“…The origin of fast and slow PL decays in group III-nitride semiconductors has been the subject of a number of previous studies [15,19,[41][42][43][44][45]. After Refs.…”

“…Such FKOs features have been commonly observed in PR spectra of III-V semiconductors and structures and have been attributed to the modulation of the built-in electric fields present at the layer surface and/or layers' interfaces [30,31,49,50]. To obtain the electric field of the AlGaN films, the FKO period is analyzed within the asymptotic expression of PR [19,49]. This approach neglects the light-hole contribution to PR spectra and takes into account only the contribution of heavy holes [49].…”

“…The structural, morphological and optical properties of the GaN template layer are investigated in Ref. [19]. Fig.…”

“…This leads to the growth of AlGaN films with a high density of defects. These defects trap carriers, acting as non-radiative recombination centers, and consequently affect the optical and electronic properties of the elaborated layers [15][16][17][18][19][20][21][22][23]. However, several methods have been suggested to reduce the effects associated with mismatches between the AlGaN layer and sapphire substrate, e.g., the deposition of a low-temperature buffer layer of GaN or AlN on the substrate [24] and the epitaxial lateral overgrowth [6].…”

Method of smoothing photoluminescence spectra

“…There is an opinion in the book [11], which is considered as one of basic sources on the problem of smoothing, that luminescent spectra must be smoothed by Savitzky-Golay method, using the window width that equals 11 or 25 points, and polynomials from quadratic to quintic inclusive. There are smoothed PL spectra in the paper [12], however it is indicated that smoothing was performed by the mathematical packages of qdot.com. The paper [13] shows the smoothed spectra of absorption; besides, it is mentioned, that the data were interpolated by means of splines, but there is no indication of which ones were used.…”