(Al, Ga)N-Based Quantum Dots Heterostructures on h-BN for UV-C Emission
Résumé
Aluminium Gallium Nitride (Al y Ga 1-y N) quantum dots (QDs) with thin sub-µm Al x Ga 1-x N layers (with x > y) were grown by molecular beam epitaxy on 3 nm and 6 nm thick hexagonal boron nitride (h-BN) initially deposited on c-sapphire substrates. An AlN layer was grown on h-BN and the surface roughness was investigated by atomic force microscopy for different deposited thicknesses. It was shown that for thicker AlN layers (i.e., 200 nm), the surface roughness can be reduced and hence a better surface morphology is obtained. Next, Al y Ga 1-y N QDs embedded in Al 0.7 Ga 0.3 N cladding layers were grown on the AlN and investigated by atomic force microscopy. Furthermore, X-ray diffraction measurements were conducted to assess the crystalline quality of the AlGaN/AlN layers and examine the impact of h-BN on the subsequent layers. Next, the QDs emission properties were studied by photoluminescence and an emission in the deep ultraviolet , i.e., in the 275-280 nm range was obtained at room temperature. Finally, temperature-dependent photoluminescence was performed. A limited decrease in the emission intensity of the QDs with increasing temperatures was observed as a result of the three-dimensional confinement of carriers in the QDs.
Mots clés
deep ultra-violet emission molecular beam epitaxy nitrides wide bandgap materials boron nitride aluminium gallium nitride quantum dots X-ray diffraction photoluminescence atomic force microscopy
deep ultra-violet emission
molecular beam epitaxy
nitrides
wide bandgap materials
boron nitride
aluminium gallium nitride
quantum dots
X-ray diffraction
photoluminescence
atomic force microscopy
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