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MOCVD growth and ultrafast photoluminescence in GaAs and InAs freestanding quantum whiskers—a review
Author(s) -
Viswanath A. Kasi,
Hiruma K.,
Yazawa M.,
Ogawa K.,
Katsuyama T.
Publication year - 1994
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.4650070306
Subject(s) - photoluminescence , materials science , picosecond , condensed matter physics , metalorganic vapour phase epitaxy , exciton , laser linewidth , band gap , molecular physics , quantum well , quantum dot , whiskers , optoelectronics , optics , chemistry , nanotechnology , laser , physics , epitaxy , layer (electronics) , composite material
Nanometer‐size quantum whiskers of InAs and GaAs have been fabricated by low‐pressure MOCVD. Time‐integrated and time‐resolved photoluminescence of GaAs wires of diameters 200, 100, 70, and 50 nm have been studied. The temperature dependence of PL peak energy was found to follow the same variation as the bandgap of GaAs, and Varshni's theory has been used to explain the temperature dependence. The main channel of radiative recombination was found to be due to free excitons. The nonuniformity in diameter and lattice phonon interactions were considered to understand the origin of the linewidth. From the time‐resolved PL the surface recombination lifetimes were measured directly. Surface recombination velocities were evaluated and were correlated to wire diameter. The quantum‐size‐dependent spatial part of the electronic wave function was thought to be responsible for the variation of surface recombination velocity with diameter. Surface treatment with sulphur reduced the surface depletion layer, as evidenced from the time‐resolved and time‐integrated spectra. The carrier lifetime was in picosecond time scales at 7 K and increased with temperature, thus confirming the quantum confinement effects. The polarization experiments revealed the one‐dimensional nature of quantum whiskers. © 1994 John Wiley & Sons, Inc.