Triple Narrowband Mid-Infrared Thermal Emitter Based on a Au Grating-Assisted Nanoscale Germanium/Titanium Dioxide Distributed Bragg Reflector: Implications for Molecular Sensing

Author(s):  
Hui-Hsin Hsiao ◽  
Chu-Han Huang ◽  
Bo-Ting Xu ◽  
Guan-Ting Chen ◽  
Po-Wei Ho
MRS Advances ◽  
2019 ◽  
Vol 4 (11-12) ◽  
pp. 661-666
Author(s):  
L. Ajith DeSilva ◽  
Sarahn Nazaret ◽  
A. G. U. Perera ◽  
T. M. W. J. Bandara

ABSTRACTOne-dimensional hybrid Distributed Bragg Reflector (DBR) is constructed using Tris (8-hydroxy) quinoline aluminum (Alq3) molecules and Titanium dioxide (TiO2) nanoparticles via spin coating process. Light emission from thin films of low molecular weight organic semiconductor of Alq3 is dominated by excitons. This material has been widely used as a superior emitter for organic light emitting diodes. Titanium dioxide (TiO2) is an inorganic semiconductor with a high band gap. Photoluminescence (PL) of thin films of Alq3 showed a broad PL peak at 530 nm. In DBR structures, PL quenching is observed but there is no shift in the PL peak of the Alq3. The PL quenching is tentatively attributed to energy transfer via sensitization to wide band gap TiO2 layers. A simple excitonic model is suggested to explain the observation. Fabrication process and optical properties of the structure are presented.


Materials ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3185 ◽  
Author(s):  
Ewelina Białek ◽  
Maksymilian Włodarski ◽  
Małgorzata Norek

In this work, the influence of a wide range anodizing temperature (5–30 °C) on the growth and optical properties of PAA-based distributed Bragg reflector (DBR) was studied. It was demonstrated that above 10 °C both structural and photonic properties of the DBRs strongly deteriorates: the photonic stop bands (PSBs) decay, broaden, and split, which is accompanied by the red shift of the PSBs. However, at 30 °C, new bands in transmission spectra appear including one strong and symmetric peak in the mid-infrared (MIR) spectral region. The PSB in the MIR region is further improved by a small modification of the pulse sequence which smoothen and sharpen the interfaces between consecutive low and high refractive index layers. This is a first report on PAA-based DBR with a good quality PSB in MIR. Moreover, it was shown that in designing good quality DBRs a steady current recovery after subsequent application of high potential (UH) pulses is more important than large contrast between low and high potential pulses (UH-UL contrast). Smaller UH-UL contrast helps to better control the current evolution during pulse anodization. Furthermore, the lower PSB intensity owing to the smaller UH-UL contrast can be partially compensated by the higher anodizing temperature.


2020 ◽  
Vol 20 (8) ◽  
pp. 5096-5101
Author(s):  
Kejie Dai ◽  
Xuan Zhao

Titanium dioxide, which leads an excellent optical performance, is proposed to design irregularly distributed Bragg reflector (IDBR) through theoretical simulation as well as experimental verification. Firstly, a primary distributed Bragg reflector (DBR) model with the titanium dioxide serving as low reflection layer in, and amorphous silicon as high reflection layer is analyzed. The titanium dioxide DBR shows much enhanced reflection bandwidth relative to the DBR with silicon dioxide. A further study suggests that a traditional titanium dioxide IDBR demonstrate much enhanced performance versus the silicon dioxide IDBR with similar structure. Besides, the reflection bandwidth of the IDBR, especially in the high wavelength range, is dramatically promoted with respect to the DBR. Finally, a novel gradient IDBR model is developed. The simulation results reveal a higher reflection bandwidth of the titanium dioxide gradient IDBR than the silicon dioxide one. The reflectance of the titanium dioxide gradient IDBR is up to 90% in a range by 300 to 1450 nm. And, the reflection bandwidth of the gradient IDBR is much improved respect to the traditional IDBR. It seems that the titanium dioxide gradient IDBR could be an efficient selection for the thin film silicon solar cells. Finally, the gradient IDBR were fabricated via plasma enhanced chemical vapor deposition (PECVD) on a silicon wafer. A further test demonstrates a reflectance over 95% in the range from 400 to 1400 nm, and verifies the simulation results.


2016 ◽  
Author(s):  
Hiroyuki Yoshinaga ◽  
Jun-ichi Hashimoto ◽  
Hiroki Mori ◽  
Yukihiro Tsuji ◽  
Makoto Murata ◽  
...  

2020 ◽  
Author(s):  
Nikolay A. Kalyuzhnyy ◽  
Viktor M. Emelyanov ◽  
Sergey A. Mintairov ◽  
Mariia V. Nahimovich ◽  
Roman A. Salii ◽  
...  

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