Lheureux G, Monavarian M, Anderson R, Decrescent R A, Bellessa J, Symonds C, Schuller J A, Speck J S, Nakamura S, DenBaars S P
Opt Express. 2020 Jun 8;28(12):17934-17943. doi: 10.1364/OE.392546.
We theoretically and experimentally investigate Tamm plasmon (TP) modes in a metal/semiconductor distributed Bragg reflector (DBR) interface. A thin Ag (silver) layer with a thickness (55 nm from simulation) that is optimized to guarantee a low reflectivity at the resonance was deposited on nanoporous GaN DBRs fabricated using electrochemical (EC) etching on freestanding semipolar (2021¯) GaN substrates. The reflectivity spectra of the DBRs are compared before and after the Ag deposition and with that of a blanket Ag layer deposited on GaN. The experimental results indicate the presence of a TP mode at ∼ 454 nm on the structure after the Ag deposition, which is also supported by theoretical calculations using a transfer-matrix algorithm. The results from mode dispersion with energy-momentum reflectance spectroscopy measurements also support the presence of a TP mode at the metal-nanoporous GaN DBR interface. An active medium can also be accommodated within the mode for optoelectronics and photonics. Moreover, the simulation results predict a sensitivity of the TP mode wavelength to the ambient (∼ 4-7 nm shift when changing the ambient within the pores from air with n = 1 to isopropanol n = 1.3), suggesting an application of the nanoporous GaN-based TP structure for optical sensing.
我们从理论和实验两方面研究了金属/半导体分布式布拉格反射器（DBR）界面中的塔姆等离子体激元（TP）模式。在通过电化学（EC）蚀刻在独立半极性（2021¯）GaN衬底上制备的纳米多孔GaN DBR上沉积了一层薄的Ag（银）层，其厚度（模拟结果为55 nm）经过优化，以确保在共振时具有低反射率。比较了Ag沉积前后DBR的反射光谱以及沉积在GaN上的连续Ag层的反射光谱。实验结果表明，在Ag沉积后，该结构在约454 nm处存在TP模式，这也得到了使用传输矩阵算法进行的理论计算的支持。能量动量反射光谱测量的模式色散结果也支持在金属 - 纳米多孔GaN DBR界面处存在TP模式。对于光电子学和光子学，有源介质也可以容纳在该模式内。此外，模拟结果预测TP模式波长对环境的灵敏度（当将孔内的环境从n = 1的空气改变为n = 1.3的异丙醇时，波长会有~4 - 7 nm的偏移），这表明基于纳米多孔GaN的TP结构在光学传感方面具有应用前景。
