Grass-like alumina coated window harnesses the full omnidirectional potential of black silicon photodiodes

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2021-11-20
Major/Subject
Mcode
Degree programme
Language
en
Pages
6
10415-10420
Series
Applied Optics, Volume 60, issue 33
Abstract
Packaged photodiodes suffer from Fresnel reflection from the package window glass, especially at high angles of incidence. This has a notable impact particularly on black silicon (b-Si) photodiodes, which have extreme sensitivity. In this work, we show that by adding a simple grass-like alumina antireflection (AR) coating on the window glass, excellent omnidirectional sensitivity and high external quantum efficiency (EQE) of b-Si photodiodes can be retained. We demonstrate that EQE increases at all angles, and up to 15% absolute increases in EQE at a 70° angle of incidence compared to conventional uncoated glass. Furthermore, even at the incidence angle of 50°, the double-sided coating provides higher EQE than bare glass at normal incidence. Our results demonstrate that grass-like alumina coatings are efficient and omnidirectional AR coatings for photodiode package windows in a wide wavelength range across the visible spectrumto near-infrared radiation.
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Citation
Kauppinen , C , Pasanen , T , Isakov , K , Serue , M , Heinonen , J , Vähänissi , V , Lipsanen , H & Savin , H 2021 , ' Grass-like alumina coated window harnesses the full omnidirectional potential of black silicon photodiodes ' , Applied Optics , vol. 60 , no. 33 , pp. 10415-10420 . https://doi.org/10.1364/AO.442415