350-nm band edge-emitting laser diodes enabled by low-dislocation-density AlGaN templates
Realization of efficient laser diodes with ultra-violet (UV) emission from ~260-360 nm would enable many applications including fluorescence-based biological agent detection, sterilization, and portable water purification. While InGaN-based laser diodes are well developed down to ~370 nm, achieving shorter UV wavelengths requires higher Al-content AlGaN alloys with increasing challenges in achieving p-type doping, strain-management, and low threading-dislocation-density (TDD) AlGaN templates. Given these challenges, few groups have reported AlGaN-based edge-emitting laser diodes (LDs) with emission <; 355 nm.[1, 2] Most recently, random lasing via Anderson localization in AlGaN nanowire structures has demonstrated a novel approach to realizing deep-UV laser diodes.[3].
High‐performance UV emitter grown on high‐crystalline‐quality AlGaN underlying layer
Al0.25Ga0.75N films were grown on a grooved‐Al0.25Ga0.75N/ AlN/sapphire template by MOVPE. The dislocation density on the grooved areas was as low as 1 × 108 cm–2. We fabricated a UVA light‐emitting diode grown on such an AlGaN underlying layer exhibiting an output power of 12 mW at a DC current of 50 mA with a peak emission wavelength of 345 nm, which corresponds to an external quantum efficiency of 6.7%. This efficiency is the highest reported to date in this wavelength region. We also fabricated a 358 nm UVA laser diode (LD) using a GaN/AlGaN MQW active layer grown on an AlGaN underlying layer. This UV LD exhibits a threshold current of 73 mA and a corresponding current density of 3.8 kA/cm2 at 7 °C. The characteristic temperature T0 was 174 K in the temperature range of 7–27 °C. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 ? 1 Rib Cotton Knitted Fabrics
This study investigates the impact of yarn count and stitch length of 100% cotton knitted fabrics. 1 × 1 ribs structured fabrics were used in this research work. The stitch length 2.50 mm, 2.52 mm, 2.60 mm, 2.70 mm, 2.80 mm and 2.96 mm were used of the yarn count of 26Ne, 28Ne and 36Ne. The areal densities of the grey fabrics were in various amounts. The impacts of yarn count and stitch length were measured concerning pilling resistance, abrasion resistance, and shrinkage and tightness factor. The result showed that the fabric pilling grade decreased while number of cycle increased. Abrasion resistance decreased but length wise shrinkage increased despite the fact that the stitch length increased. The results also exposed that the tightness factor of the fabric increased with the increase of the stitch length in both dyeing and washing state and finished state compared to grey state for the yarn count 26Ne and homogeneous result not found for yarn count 28Ne and 36 Ne. Evaluation of Impact of Yarn Count and Stitch Length on Pilling, Abrasion, Shrinkage and Tightness Factor of 1 × 1 Rib Cotton Knitted Fabrics