Ordered arrays of InGaN/GaN dot-in-a-wire nanostructures as single photon emitters

Abstract

The realization of reliable single photon emitters operating at high temperature and located at predetermined positions still presents a major challenge for the development of solid-state systems for quantum light applications. We demonstrate single-photon emission from two-dimensional ordered arrays of GaN nanowires containing InGaN nanodisks. The structures were fabricated by molecular beam epitaxy on (0001) GaN-on-sapphire templates patterned with nanohole masks prepared by colloidal lithography. Low-temperature cathodoluminescence measurements reveal the spatial distribution of light emitted from a single nanowire heterostructure. The emission originating from the topmost part of the InGaN regions covers the blue-to-green spectral range and shows intense and narrow quantum dot-like photoluminescence lines. These lines exhibit an average linear polarization ratio of 92%. Photon correlation measurements show photon antibunching with a g (2) (0) values well below the 0.5 threshold for single photon emission. The antibunching rate increases linearly with the optical excitation power, extrapolating to the exciton decay rate of ~1 ns -1 at vanishing pump power. This value is comparable with the exciton lifetime measured by time-resolved photoluminescence. Fast and efficient single photon emitters with controlled spatial position and strong linear polarization are an important step towards high-speed on-chip quantum information management.

Dynamic control of the optical emission from GaN/InGaN nanowire quantum dots by surface acoustic waves

“…1(b). We employed floating electrode unidirectional IDTs 22 with a length of ∼700 µm and an aperture of ∼400 µm (approximately equal to the IDT finger length) designed to generate SAWs with an acoustic wavelength of λ SAW = 11.67 µm, corresponding to a SAW frequency and period of f SAW = 338 MHz and T SAW = 2.96 ns, respectively, at the measurement temperature T = 10 K. Note that the exciton decay time in these nanowire-QDs is ∼1.3 ns, 18 i.e. comparable to T SAW /2.…”

“…1(b)). Because the excitation energy (E exc = 2.805 eV) is lower than the radiative transitions related to the GaN nanowire 25 and the InGaN region formed on semi-polar side facets, 18 carriers are only generated in the apex of the InGaN disk. A typical low-temperature µ-PL spectrum recorded at laser excitation power P exc = 6 µW from dispersed nanowires consists of a series of sharp QD lines on top of a broader background emission.…”

“…The nitride-based dot-in-a-nanowire heterostructures presented here are efficient SPS 18 and can be precisely arranged in periodic two-dimensional arrays. 19 Thus, the present results are an important step towards the development of single photon sources working at high temperature, 20 high repetition rates and broad spectral range, 18 with simultaneous spatial and time control. The InGaN/GaN nanowire heterostructures were fabricated by plasma-assisted molecular beam epitaxy (PA-MBE) on (0001) GaN-on-sapphire templates.…”

“…This profile determines the shape of the InGaN nano-disks embedded inside the GaN nanowire tips. 18,21 The transmission electron microscope (TEM) micrograph of an individual nanowire in Fig. 1(a) reveals the presence of two InGaN sections: a thicker one (∼30 nm) formed on the polar facet close to the nanowire top and a narrower (∼20 nm thick) one on semi-polar side facets.…”

“…1(a) reveals the presence of two InGaN sections: a thicker one (∼30 nm) formed on the polar facet close to the nanowire top and a narrower (∼20 nm thick) one on semi-polar side facets. As detailed in our previous work, 18 the QDs under study are formed by fluctuations of the indium content in the topmost InGaN region.…”