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Compact Al0.37In0.63N layers were grown by radiofrequency sputtering on bare and 15 nm-thick AlN-buffered Si (111) substrates. The crystalline quality of the AlInN layers was studied by high-resolution X-ray diffraction measurements and transmission electron microscopy. Both techniques show an improvement of the structural properties when the AlInN layer is grown on a 15 nm-thick AlN buffer. The layer grown on bare silicon exhibits a thin amorphous interfacial layer between the substrate and the AlInN, which is not present in the layer grown on the AlN buffer layer. A reduction of the density of defects is also observed in the layer grown on the AlN buffer. [ABSTRACT FROM AUTHOR]

III-nitride resonant cavity-enhanced Schottky barrier photodetectors were fabricated on 2 µm thick GaN templates by radio frequency plasma-assisted molecular beam epitaxy. The optical cavity was formed by a bottom distributed Bragg reflector based on 10 periods of Al0.3Ga0.7N/GaN, an Au-based Schottky contact as top mirror, and an active zone of 40 nm-thick GaN layer. The devices were fabricated with planar geometry. To evaluate the main benefits allowed by the optical cavity, conventional Schottky photodetectors were also processed. The results revealed a planar spectral response for the conventional photodetector, unlike the resonant devices that showed two raised peaks at 330 and 358 nm with responsivities of 0.34 and 0.39 mA/W, respectively. Both values were 80 times higher than the planar response of the conventional device. These results demonstrate the strong effect of the optical cavity to achieve the desired wavelength selectivity and to enhance the optical field thanks to the light resonance into the optical cavity. The research of such a combination of nitride-based Bragg mirror and thin active layer is the kernel of the present paper. [ABSTRACT FROM AUTHOR]

III-nitride semiconductors have wide bandgap and high carrier mobility, making them suitable candidates for light-emitting diodes (LEDs), laser diodes (LDs), high electron mobility transistors (HEMTs) and other optoelectronics. Compared with conventional epitaxy technique, van der Waals epitaxy (vdWE) has been proven to be a useful route to relax the requirements of lattice mismatch and thermal mismatch between the nitride epilayers and the substrates. By using vdWE, the stress in the epilayer can be sufficiently relaxed, and the epilayer can be easily exfoliated and transferred, which provides opportunities for novel device design and fabrication. In this paper, we review and discuss the important progress on the researches of nitrides vdWE. The potential applications of nitride vdWE are also prospected. [ABSTRACT FROM AUTHOR]

Phase-separated semiconductors containing magnetic nanostructures are relevant systems for the realization of high-density recording media. Here, the controlled strain engineering of Ga δ FeN layers with Fe y N embedded nanocrystals (NCs) via Al x Ga 1 − x N buffers with different Al concentration 0 < x Al < 41 % is presented. Through the addition of Al to the buffer, the formation of predominantly prolate-shaped ε -Fe 3 N NCs takes place. Already at an Al concentration x Al ≈ 5% the structural properties—phase, shape, orientation—as well as the spatial distribution of the embedded NCs are modified in comparison to those grown on a GaN buffer. Although the magnetic easy axis of the cubic γ '-Ga y Fe 4 − y N nanocrystals in the layer on the x Al = 0 % buffer lies in-plane, the easy axis of the ε -Fe 3 N NCs in all samples with Al x Ga 1 − x N buffers coincides with the [ 0001 ] growth direction, leading to a sizeable out-of-plane magnetic anisotropy and opening wide perspectives for perpendicular recording based on nitride-based magnetic nanocrystals. [ABSTRACT FROM AUTHOR]

Hexagonal boron nitride (hBN) has attracted a great deal of attention as a key component in van der Waals (vdW) heterostructures, and as a wide band gap material for deep-ultraviolet devices. We have recently demonstrated plasma-assisted molecular beam epitaxy (PA-MBE) of hBN layers on substrates of highly oriented pyrolytic graphite at high substrate temperatures of ~1400 °C. The current paper will present data on the high-temperature PA-MBE growth of hBN layers using a high-efficiency radio-frequency (RF) nitrogen plasma source. Despite more than a three-fold increase in nitrogen flux with this new source, we saw no significant increase in the growth rates of the hBN layers, indicating that the growth rate of hBN layers is controlled by the boron arrival rate. The hBN thickness increases to 90 nm with decrease in the growth temperature to 1080 °C. However, the decrease in the MBE temperature led to a deterioration in the optical properties of the hBN. The optical absorption data indicates that an increase in the active nitrogen flux during the PA-MBE process improves the optical properties of hBN and suppresses defect related optical absorption in the energy range 5.0–5.5 eV. [ABSTRACT FROM AUTHOR]