Tailoring the shape of GaN/AlxGa1−xN nanostructures to extend their luminescence in the visible range

Abstract

We show that the shape of GaN nanostructures grown by molecular beam epitaxy on AlxGa1−xN (0001) surfaces, for x≥0.4, can be controlled via the ammonia pressure. The nanostructures are obtained from a two dimensional to three dimensional transition of a GaN layer occurring upon a growth interruption. Atomic force microscopy measurements show that depending on the ammonia pressure during the growth interruption, dot or dash-shaped nanostructures can be obtained. Low temperature photoluminescence measurements reveal a large redshift in the emission energy of the quantum dashes, as compared to the quantum dots. By simply adjusting the GaN deposited thickness, it is shown that quantum dashes enable to strongly extend the emission range of GaN/Al0.5Ga0.5N nanostructures from the violet-blue (∼400–470 nm) to the green-orange range (∼500–600 nm).

GaN:Pr3+ nanostructures for red solid state light emission

“…16 The use of GaN quantum structures like QWs or QDs also offers some benets due to the spatial connement effects of the carriers. 18,19 For instance, QDs can capture carriers that will occupy strongly localized states limiting their migration toward the defects that are formed during the growth process. 18 Previous reported works revealed that GaN QDs grown in a AlN matrix can be efficient light emitters even when grown on highly mismatched substrate such as silicon.…”

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

“…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.…”

“…GaN nanostructures have been grown on polar-(0001) and semipolar- (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) planes by molecular beam epitaxy. The nanostructures are obtained by triggering a 2D-3D morphological transition of the GaN layer grown on Al 0.5 Ga 0.5 N. The formation of nanostructures is done during a growth interruption in vacuum.…”

“…QDs, QDashes, quantum wires (QWRs) and QWs) can be grown on Al 0.5 Ga 0.5 N surfaces by modifying different growth parameters: the GaN deposited thickness amount, the NH 3 pressure or the surface orientation. 13,14,15 Furthermore, we have demonstrated that the nanostructure design leads to particular optical properties (emitted wavelength range, temperature dependence, system dimensionality etc.). 14,16 In this paper, the formation, morphological and optical properties of (0001) "polar" and (11 2 2) "semipolar" GaN nanostructures will be presented and compared, using different experimental techniques.…”

“…13,14,15 Furthermore, we have demonstrated that the nanostructure design leads to particular optical properties (emitted wavelength range, temperature dependence, system dimensionality etc.). 14,16 In this paper, the formation, morphological and optical properties of (0001) "polar" and (11 2 2) "semipolar" GaN nanostructures will be presented and compared, using different experimental techniques. In particular, the influence of the internal electric field in the structures will be discussed.…”