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

Christoffer Kauppinen*, Toni Pasanen, Kirill Isakov, Michael Serue, Juha Heinonen, Ville Vähänissi, Harri Lipsanen, Hele Savin

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
99 Downloads (Pure)

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.

Original languageEnglish
Pages (from-to)10415-10420
Number of pages6
JournalApplied Optics
Volume60
Issue number33
DOIs
Publication statusPublished - 20 Nov 2021
MoE publication typeA1 Journal article-refereed

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