Nanowire GRINSCH diode for UV applications

Semiconductor Today features "KAUST demonstrates nanowire GRINSCH diode for efficient UV-LED/laser applications"

"AlGaN-based light-emitting devices are promising ultraviolet light sources to replace the existing UV gas lasers and UV lamps containing toxic substances (mercury). However, the performance of AlGaN-based UV emitters are limited, and in particular high-power UV laser diodes (emitting below 330nm) have not yet been reported. Moreover, the threshold operating voltages of reported UV laser diodes (>330nm) are quite high, surpassing 25V in lasing mode with high series resistance due to poor hole injection efficiency."

"These limitations in device performance are attributed to several factors such as the presence of a high density of defects (dislocations) and inefficient p-type doping of the Al-rich AlGaN layers, and the lack of efficient thermal dissipation channels for existing device schemes. A new device scheme is therefore urgently needed."

"AlGaN nanowires, however, are found to be promising candidates to overcome these obstacles. Compared with AlGaN epitaxial thin-film layers, defect-free AlGaN nanowires can be grown directly on many substrates (including metals) due to the efficient strain relaxation associated with the large surface-to-volume ratio. ... Ultimately, low defect/dislocation density, low turn-on voltage and small sheet resistance, and better heat dissipation channels are the key prerequisites for achieving high-performance III-nitride based UV and visible devices. ..."

Graded-Index Separate Confinement Heterostructure AlGaN Nanowires: Toward Ultraviolet Laser Diodes Implementation

Haiding Sun, Davide Priante, Jung-Wook Min, Ram Chandra Subedi, Mohammad Khaled Shakfa, Zhongjie Ren, Kuang-Hui Li, Ronghui Lin, Chao Zhao, Tien Khee Ng, Jae-Hyun Ryou, Xixiang Zhang, Boon S. Ooi, and Xiaohang Li
ACS Photonics, Article ASAP (2018)

DOI: 10.1021/acsphotonics.8b00538