Strain induced power enhancement of far-UVC LEDs on high temperature annealed AlN templates
Strain induced power enhancement of far-UVC LEDs on high temperature annealed AlN templates
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DOI：
10.1063/5.0134253
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发表时间：
2023-01-02
影响因子：
4
通讯作者：
Weyers, M.
中科院分区：
文献类型：
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作者：
Knauer, A.;Kolbe, T.;Weyers, M.
高温退火的AlN/蓝宝石模板表现出降低的面内晶格常数相比，传统的非退火的AlN/蓝宝石生长的金属有机气相外延（MOVPE）。这导致模板和在这些模板上生长的AlGaN基紫外-C发光二极管（UVC LED）异质结构之间的额外晶格失配。这种失配在AlGaN量子威尔斯阱中引入了额外的压缩应变，导致与沉积在常规MOVPE生长的AlN模板上的层结构相比，在低于235 nm的波长处量子阱发射的横向电极化增强，所述层结构主要表现出横向磁极化发射。此外，高温退火的AlN/蓝宝石模板还具有降低的缺陷密度，从而减少非辐射复合。基于这两个因素，即，通过提高横向电偏振光的外耦合效率和内量子效率，进一步改善了231 nm远紫外LED的性能，在150 mA时连续光输出功率为3.5 mW。
High temperature annealed AlN/sapphire templates exhibit a reduced in-plane lattice constant compared to conventional non-annealed AlN/sapphire grown by metalorganic vapor phase epitaxy (MOVPE). This leads to additional lattice mismatch between the template and the AlGaN-based ultraviolet-C light emitting diode (UVC LED) heterostructure grown on these templates. This mismatch introduces additional compressive strain in AlGaN quantum wells resulting in enhanced transverse electric polarization of the quantum well emission at wavelengths below 235 nm compared to layer structures deposited on conventional MOVPE-grown AlN templates, which exhibit mainly transverse magnetic polarized emission. In addition, high temperature annealed AlN/sapphire templates also feature reduced defect densities leading to reduced non-radiative recombination. Based on these two factors, i.e., better outcoupling efficiency of the transverse electric polarized light and an enhanced internal quantum efficiency, the performance characteristic of far-UVC LEDs emitting at 231 nm was further improved with a cw optical output power of 3.5 mW at 150 mA.