Modulation spectroscopy of InAs semiconductor nanostructures grown on (631) high index substrates

Abstract

The molecular beam epitaxial (MBE) growth of InAs nanostructures on GaAs(631)‐oriented substrates is studied by photoluminescence (PL) and photoreflectance spectroscopy (PR). First, a corrugated surface conformed by regularly spaced grooves aligned along the [$ \bar 5 $93] azimuth was formed by the GaAs homoepitaxial growth on the (631) substrate. On this template, we proceeded with the deposition of InAs at several thicknesses in the range of 1 to 4.5 monolayers (MLs). An atomic force microscopy (AFM) analysis of samples without GaAs capping, revealed that assemblage of QDs occurs only after the deposition of the equivalent to ∼1.9 ML of InAs. On these samples, we observed changes on the PR line‐shape in the near‐bandgap GaAs region linked to the quantity of InAs deposited. The intensity of the built in electric fields was correlated with the strain state at the heterointerface, as a consequence of the self induced piezoelectric effect, typical from high index surfaces. On the other hand, when the samples were capped with a 100 Å thick GaAs layer, strong emission of the nanostructures occurs even for deposited quantities of InAs as low as 1 ML. Since for this InAs thickness the self‐assemblage of QDs is not observed, the optical transitions observed were associated with the optical emission of self assembled semiconductor quantum wires, promoted by surface diffusion anisotropy, characteristic of the (631) plane. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Polarization and Excitation Dependence of Photoluminescence of InAs Quantum Wires and Dots Grown on GaAs(631)

“…Thus, it is suggested that the origin of these lines is related to low-dimensional systems. 6) To further clarify the nature of the emission lines, a polarizer was placed at the entrance slit of the monochromator to perform PL measurements with polarization along the ½ " 113 and ½ " 8; 19; " 9 directions, i.e., parallel and perpendicular to the nanoscale step arrays. As observed in Fig.…”

“…The peculiar atomic arrangements of the top most atoms on high-index substrates lead to interesting surface diffusion properties that can be used to obtain self assembled quantum wires (SAQWRs) and/or to align QDs. 6) In this work, we studied the optical properties of selfassembled InAs nanostructures grown by MBE on GaAs substrates with ð " 6 " 3 " 1Þ crystallographic orientation by photoluminescence (PL) spectroscopy. The 1D electron confinement in the heterostructures was corroborated by PL polarized along two orthogonal directions.…”

InxGa1−xAs quantum wire network‐like and ordered checker board‐like nanostructures on GaAs (311) by low In composition multi‐layer stacking

“…Due to their interesting nature of self‐assembly and exhibited quantum confinement, low‐dimensional semiconductor strained In x Ga 1− x As quantum structures on high index GaAs have gained a significant research attention 1–3. As a result, such optoelectronic device applications as light‐emitting diodes, amplifiers, solar cells, laser, and detectors have been demonstrated 4–9.…”