Sputtering AlN/InxAl1-xN distributed Bragg reflector across the full visible range on Si and SiO2 substrates.

III-nitride-based distributed Bragg reflectors (DBRs) are advantageous in being in-situ integrated in III-nitride devices, and the bandgaps and their other corresponding optical parameters are tunable. However, a growing nitride DBR with low strain and high reflectivity remains a challenge. Here we demonstrate an AlN/InxAl1-xN DBR grown on Si and SiO2 substrates by reactive radio-frequency magnetron sputtering. Reflectance wavelengths covering the whole visible regions of the visible spectrum were achieved by rationally tuning the indium composition in InxAl1-xN and each layer's thickness of an AlN/InxAl1-xN DBR. This Letter should advance the design and fabrication of nitride optical and optoelectrical devices by incorporating an AlN/InxAl1-xN DBR, such as vertical-cavity surface-emitting laser (VCSEL) and RC LEDs.

Ultrawide bandgap AlN metasurfaces for ultraviolet focusing and routing.

All-dielectric metasurfaces offer a promising way to control amplitude, polarization, and phase of light. However, ultraviolet (UV) component metasurfaces are rarely reported due to significant absorption loss for most dielectric materials and the required smaller footprint or feature size. Here, we demonstrate broadband UV focusing and routing in both transmission and reflection modes in simulations by adopting aluminum nitride (AlN) with ultrawide bandgap and a waveplate metasurface structure. As for experiments, the on-axis, off-axis focusing characteristics in transmission mode have been investigated at representative UVA (375 nm) wavelength for the first time, to the best of our knowledge. Furthermore, we fabricated a UV transmission router for monowavelength, guiding UV light to the designated different spatial positions of the same or different focal planes. Our work is meaningful for the development of UV photonics components and devices and would facilitate the integration and miniaturization of UV nanophotonics.

Three-dimensional metal-semiconductor-metal AlN deep-ultraviolet detector.

Conventional metal-semiconductor-metal (MSM) ultraviolet (UV) detectors have the disadvantage of limited adjustable structural parameters, finite electrical field, and long carrier path. In this Letter, we demonstrate a three-dimensional (3D) MSM structural AlN-based deep-UV (DUV) detector, fabricated through simple trench etching and metal deposition, while flip bonding to the silicon substrate forms a flip-chip 3D-MSM (FC-3DMSM) device. 3D-MSM devices exhibit improved responsiveness and response speed, compared with conventional MSM devices. Time-dependent photoresponse of all devices is also investigated here. The enhanced performance of the 3D-MSM device is to be attributed to the intensified electrical field from the 3D metal electrode configuration and the inhibition of the carrier vertical transport, which unambiguously increases the carrier collection efficiency and migration speed, and thus the responsivity and speed as well. This work should advance the design and fabrication of AlN-based DUV detectors.