Power- and temperature-dependent photoluminescence investigation of carrier localization at inverted interface transitions in InAlAs/InP structures

Abstract

We report on combined photoluminescence (PL) and micro-Raman microscopy to study the effect of the V/III flux ratio on InAlAs ternary alloy grown on (311)A InP by metal-organic chemical vapor deposition. The PL of the type-II transition was studied in a wide range of temperatures (10–300 K) and excitation intensities. As the V/III flux ratio increased from 25 to 125, a redshift of the type-II transition was observed. Then, micro-Raman investigations showed the presence of an LO mode related to LO-like InAs in InAsP alloy at the inverted interface in our samples. Furthermore, we discuss the effect of laser excitation wavelength on the Raman spectrum. We also note that phonon peaks are very sensitive to different excitation sources (364 to 638 nm). At lower frequencies, disorder-activated longitudinal acoustic phonons are also observed, which consider the presence of potential fluctuations. This last generate the carrier’s localization, which confirmed by PL measurements. In all samples, a blueshift of the type-II transition is noted with increasing the excitation power, which may reflect the presence of carrier localization, whereas the temperature-dependent PL peak energy displayed unusual behavior, such as consecutive red–blue–redshift (S-shaped) behavior and an inverted N-shape in the full width at half maximum. These unusual behaviors are explained by carriers captured by localized recombination centers. Moreover, in the room temperature PL spectra two types of emission were detected at 1.3 and 1.55 μm.