Effects of capping on GaN quantum dots deposited on Al0.5Ga0.5N by molecular beam epitaxy

Abstract

Articles you may be interested inStark effect in ensembles of polar (0001) Al0.5Ga0.5N/GaN quantum dots and comparison with semipolar (11−22) ones J. Appl. Phys. 116, 034308 (2014); 10.1063/1.4889922 Mechanism of GaN quantum dot overgrowth by Al0.5Ga0.5N: Strain evolution and phase separation J. Appl. Phys. 111, 084309 (2012); 10.1063/1.4704682 GaN quantum dot superlattices grown by molecular beam epitaxy at high temperature Investigation of AlN films grown by molecular beam epitaxy on vicinal Si(111) as templates for GaN quantum dots Appl.Influence of AlN overgrowth on structural properties of GaN quantum wells and quantum dots grown by plasma-assisted molecular beam epitaxy

Growth of GaN nanostructures with polar and semipolar orientations for the fabrication of UV LEDs

“…QDs) grown on (0001) Al 0.5 Ga 0.5 N layers ( fig. 4(a)), which have been found to be pyramids with a hexagonal basis, 21 in the case of the (11 2 2)-oriented layers, we observe chains of QDs elongated and ordered along the <1 1 00> axis ( fig. 4(b)).…”

“…15 In both cases, the typical nanostructure width is found between 15 and 25 nm. As the GaN deposited amount is increased, the nanostructure height varies between 3 to 5 nm and 1 to 4 nm in the polar 21 and semipolar case, 16 respectively. Next, the PL properties of the nanostructures have been studied as a function of temperature, and compared to reference structures made of QWs ( figure 6).…”

“…32 In particular, a systematic study aiming at investigating the optical characteristics of GaN nanostructures of as a function of their shape, size and density to determine their potential as UV emitters has been done very recently. 33 Results point out the existence of a trade-off between the GaN deposited amount (to control the nanostructure dimensions) and the QD density in order to obtain high radiative efficiencies at shorter wavelengths, along with the necessity of a reduction (suppression) of the internal electric field by using the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) orientation.…”

“…The (0001)-oriented QDs have a truncated hexagonal pyramidal shape with facets parallel to {1 1 03} planes. 21 In the case of semipolar QDs ( fig. 4(b)), the nanostructures have an asymmetrical shape with the facet on the right side of the image corresponding to a (11 2 0) plane, the top facet to (11 2 2), and the facet on the left side to a (11 2 3) plane.…”

Recent TEM developments applied to quantum structures

“…The most attractive zones for newly deposited Ga adatoms correspond to the regions having an in-plane local lattice constant equal to that of unstrained GaN. Ga atoms will accumulate at the upper edges of the dots which can contribute to the increase of their lateral size [14]. It is thus expected that the produced phase separation increases the Ga concentration in the vicinity of the dots (as open V-shaped arms) at the expense of the Ga concentration in the AlGaN alloy.…”