Recently, a research team from Xiamen University innovatively designed a chamfered pyramid/table-shaped artificial nanostructure. Through the combination of nanoimprinting, dry etching technology and wet etching process, the light emission wavelength is as short as 234 nm (AlN )8/(GaN)2 The active layer forms (0001), (10-13) and (20-21) groups of crystal planes with finely controllable angles. Interestingly, these crystal planes can control the propagation and extraction mode of deep ultraviolet light waves in nanostructures, effectively breaking through the limitation of the small cone angle of outgoing light in traditional planar structures, and greatly improving the extraction efficiency of deep ultraviolet light.
The research shows that after the introduction of the crystal face-controllable inverted pyramid/table structure, the TM and TE polarized light are enhanced by 5.6 times and 1.1 times, respectively, compared with the planar structure, and the total luminous intensity at the deep ultraviolet wavelength of 234 nm is increased by nearly 2%. times. This research work provides a new idea for improving the efficiency of deep ultraviolet short-wave light-emitting devices, and is expected to be extended to optoelectronic devices such as micro-sized LEDs and deep ultraviolet detectors.
Figure 1. (a) Schematic diagram of the fabrication process of nanopore arrays by nanoimprinting; (b)-(c) Structural characterization of (AlN)8/(GaN)2 ultrashort-period superlattices; (d)-( f) Microscopic shapes of nanoholes and (g)-(h) inverted pyramid/table nanohole arrays
Figure 2. (a) Photoluminescence spectra of conventional planar, circular nanoholes and chamfered pyramid/table nanoholes; (b) Internal quantum efficiency, TE/TM light extraction efficiency and overall luminous intensity enhancement of the three nanostructures Factor distribution plot.
The related research results were published in the Royal Society of Chemistry journal Nanoscale under the title of "Enhancing deep-UV emission at 234 nm by introducing a truncated pyramid AlN/GaN nanostructure with fine-tuned multiple facets" and recommended as the cover research work of the journal ( Back Inside Cover). The relevant testing work was supported by the research group of Professor Yang Zhizhong of National Taiwan University.
