Photodetectors for the ultraviolet (UV) range of the electromagnetic spectrum are in great demand for several technologies, but require the development of novel device structures and materials. Here we report on the high detectivity of UV photodetectors based on well-ordered laterally mesoporous GaN. The specific detectivity of our devices under UV-illumination reaches values of up to 5.3 × 10 Jones. We attribute this high specific detectivity to the properties of the mesoporous GaN/metal contact interface: the trapping of photo-generated holes at the interface lowers the Schottky barrier height thus causing a large internal gain. High detectivity along with a simple fabrication process endows these laterally mesoporous GaN photodetectors with great potential for applications that require selective detection of weak optical signals in the UV range.

Since the terrain slope cannot be neglected for forest height inversion with polarimetric synthetic aperture radar interferometry (PolInSAR), a sloped random volume over ground (S-RVoG) model is proposed to correct the terrain distortion for forest parameters estimation. A significant model complexity reduction is achieved by aligning the reference frame along the local terrain slope and changing the corresponding radar geometrical configuration. The proposed S-RVoG model inversion promises to provide much more accurate estimation of forest parameters and is validated with L-band PolInSAR data produced by PolSARpro software developed by the European Space Agency (ESA).

A novel nanopattern technique of nanospherical-lens photolithography is introduced to fabricate the InGaN nanopyramid white (NPW) light-emitting diodes (LEDs) by selective area growth. Highly ordered NPW LED arrays are achieved after optimizing the growth conditions. It is found that the NPW LEDs vary from warm white light to cool with the increase in growth temperature. For the cool white NPW LEDs, the spectrum is similar to the conventional white LEDs obtained from the blue LEDs combined with yellow phosphors. The blue emission originates from the upper sidewalls of nanopyramids, and yellow light is mainly emitted from the lower ridges with respect to the base of nanopyramids. Furthermore, simulation shows that the light extraction efficiency of NPW LEDs is about 4 times higher compared with conventional ones, and the escape cone is as much as 85° due to their three-dimensional nanopyramid structures. These observations suggest that the proposed phosphor-free NPW LEDs may have great potential for highly efficient white lighting.