Yu, PY Su, ZP Kim, DS Khim, JS Lim, YS Yee, YH Cho, YH Lee, JS Lee, JH Chang, JS Choe, BD Woo, DH Shin, EJ Kim, D Arya, K Song, JJ 2024-01-21T19:11:23Z 2024-01-21T19:11:23Z 2022-01-11 1996-10-15 0163-1829 https://pubs.kist.re.kr/handle/201004/144265 We develop a theoretical model to analyze a nonequilibrium optical- (LO-) phonon population by Raman scattering in GaAs/AlxGa1-xAs quantum webs. With the assumption of bulklike hot-electron relaxation, the effect of LO-phonon confinement on a nonequilibrium optical-phonon population (NOP) is isolated. Our analysis shows that the decrease in spatial extent or coherence length of LO phonons is reflected by a decrease in NOP. This is because the contributions from large q wave vectors with small occupation numbers dominate as the spatial extent decreases. Our method is applied to explain picosecond Raman-scattering experiments on GaAs/AlxGa1-xAs. The increasing NOP with decreasing x is interpreted as the result of an increase in the coherence length of LO phonons, since for smaller x, the AlxGa1-xAs barrier is no longer effective in localizing GaAs LO phonons within the well. Using this model, we also deduce coherence length of LO phonons as a function of x. Our results show that for values of x between 0.2 and 0.4, the GaAs LO phonon in GaAs/AlxGa1-xAs quantum wells changes from a bulklike propagating mode to one localized within the wells. English AMERICAN PHYSICAL SOC SUBPICOSECOND RAMAN-SCATTERING SCANNING-TUNNELING-MICROSCOPY SHORT-PERIOD SUPERLATTICES LO PHONONS INTERVALLEY SCATTERING SEMICONDUCTOR ALLOYS PICOSECOND RAMAN GAAS SPECTROSCOPY GENERATION Probing optical-phonon propagation in GaAs/AlxGa1-xAs quantum-well samples via their nonequilibrium population Article 10.1103/PhysRevB.54.10742 1 PHYSICAL REVIEW B, v.54, no.15, pp.10742 - 10750 PHYSICAL REVIEW B 54 15 10742 10750 scie scopus A1996VT67400078 Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Materials Science Physics Article SUBPICOSECOND RAMAN-SCATTERING SCANNING-TUNNELING-MICROSCOPY SHORT-PERIOD SUPERLATTICES LO PHONONS INTERVALLEY SCATTERING SEMICONDUCTOR ALLOYS PICOSECOND RAMAN GAAS SPECTROSCOPY GENERATION