Stacking InAs islands and GaAs layers: Strongly modulated one-dimensional electronic systems

Abstract

With chemical beam epitaxy we stacked small InAs islands, separated by thin GaAs layers. Reflection electron diffraction during growth showed that after a seed-layer growth, subsequent depositions require less InAs to form the islands. At 5 K the stacks have narrower luminescence peaks at lower energies than single island layers, and the stacks luminesce at room temperature. For 4-nm-high pyramidal islands with 20-nm-wide bases, we observed vertical periods down to 5.4 nm, small enough to couple quantum mechanically. The electronic structures possible for this class of objects should be sufficient for designing and observing room temperature quantum mechanical phenomena.

Spontaneous Superlattice Formation in Nanorods Through Partial Cation Exchange

“…In epitaxially grown systems, the interface between the substrate crystal and the quantum dot creates a region of strain surrounding the dot. Ingeniously, this local strain has been used to create an energy of interaction between closely spaced dots; this use of "strain engineering" has led, in turn, to quantum dot arrays which are spatially patterned in two (and even three) dimensions (2)(3)(4). In this paper, we demonstrate the application of strain engineering in a colloidal quantum dot system, by introducing a method that spontaneously creates a regularly spaced arrangement of quantum dots within a colloidal quantum rod.…”

Enhancement of device performance by using quaternary capping over ternary capping in strain-coupled InAs/GaAs quantum dot infrared photodetectors

“…To meet the standard for the commercial application of infrared detectors and upgrade the performance of optoelectronic devices, the development of a defect-free highly uniform and vertically ordered QD array over a large area is essential. The introduction of a strain-reducing layer above the QDs has proved to be efficient in improving the growth of ordered QDs in a vertical manner [10,11]. Multilayer QD stacks have demonstrated an increased absorption coefficient and thermal stability.…”

Today's challenges in quantum dot materials research for tomorrow's quantum functional devices

“…Due to the electronic coupling the PL of these closely stacked QDs is red shifted by about 90 nm compared to that of the stacked QDs with 40 nm separation layer thickness, as is commonly observed [22][23][24], and the PL linewidth at low temperature is reduced by more than 30 meV. The wavelength tuning efficiency upon GaAs interlayer thickness remains unchanged as well as the high structural and optical quality which is confirmed by the one order of magnitude larger PL efficiency at RT compared to that of the single QD layers.…”