Self-assembled Al
y
Ga1−
y
N quantum dots (QDs), with y = 0 and 0.1, have been grown by molecular beam epitaxy on Al0.5Ga0.5N(0001) oriented layers using sapphire substrates. The QD formation has been followed in situ by reflection high energy electron diffraction (RHEED). A two- to three-dimensional (2D–3D) transition of the layer morphology is observed, characterized by a change of the RHEED pattern from streaky lines to Bragg spots. High QD densities, from 1010 up to near 1012 cm−2, have been obtained. By decreasing the GaN QD size and incorporating Al inside the QDs, a strong variation in the photoluminescence (PL) emission has been observed, enabling to cover a large spectral range from near UV (3 eV) to UV-B (3.95 eV). By combining temperature-dependent and time-resolved PL measurements, the internal quantum efficiency of the QDs has been determined at both low and high temperatures as a function of the PL energy.
AlyGa1-yN quantum dots (QDs) have been grown by molecular beam epitaxy on AlxGa1-xN (0001) using a 2 dimensional -3 dimensional growth mode transition that leads to the formation of QDs. QDs have been grown for Al compositions y varying between 10% and 40%. The influence the active region design (composition y, QD height and band gap difference (ΔEg) between the AlxGa1-xN cladding layer and the AlyGa1-yN QDs) is discussed based on microscopy, continuous wave photoluminescence (PL) and time-resolved PL (TRPL) measurements. In particular, increasing y leads to a shift of the QD emission towards shorter wavelengths, allowing covering a spectral range in the UV from 332 nm (UVA) to 276 nm (UVC) at room temperature (RT). The low temperature (LT)
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