Attempts to grow optically coupled Fibonacci-spaced InGaAs/GaAs quantum wells result in surface gratings.
An instability in the growth of nonperiodic InGaAs/GaAs multiple quantum well samples, ordinarily of high-quality when grown with equal periods of order of half the wavelength of light in the material, leads to a dramatic microscopic, self-organized surface grating. This effect was discovered while growing quantum wells with two unequal barrier lengths arranged in a Fibonacci sequence to form an optical quasicrystal. A laser beam incident normal to the surface of the sample is diffracted into a propeller-shaped pattern. The sample surface has a distinctly cloudy appearance when viewed along one crystal axis but is mirror-like when the sample is rotated 90 degrees. The instability results in a five-fold increase in the absorption linewidth of the heavy-hole exciton transition. Atomic force microscopy, transmission electron microscopy, and scanning electron microscopy were used to study the samples.
Richards
B C
BC
College of Optical Sciences, The University of Arizona, Tucson, AZ 85721, USA. brichards@optics.arizona.edu
Hendrickson
J
J
Sweet
J
J
Khitrova
G
G
Litvinov
D
D
Gerthsen
D
D
Myer
B
B
Pau
S
S
Sarid
D
D
Wegener
M
M
Ivchenko
E L
EL
Poddubny
A N
AN
Gibbs
H M
HM