Nanostructured germanium with >99% absorption at 300-1600 nm wavelengths

Toni Pasanen, Joonas Isometsä, Moises Garin, Kexun Chen, Ville Vähänissi, Hele Savin

Research output: Contribution to journalArticleScientificpeer-review

16 Citations (Scopus)
36 Downloads (Pure)


Near-infrared (NIR) sensors find numerous applications within various industry fields, including optical communications and medical diagnostics. However, the state-of-the-art NIR sensors made of germanium (Ge) suffer from rather poor response, largely due to high reflection from the illuminated device surface. This work demonstrates a method to increase the sensitivity of Ge sensors by implementing nanostructures to the wafer surfaces. The absorbance of nanostructured Ge wafers is measured to be >99% in the whole UV–vis–NIR spectrum up to 1600 nm wavelength, which is a significant improvement to bare Ge wafers that reach absorption of only 63% in maximum. The process is shown to be capable of producing uniform nanostructures covering full 100 mm diameter substrates as well as wafers with etch mask openings of different sizes and shapes, which demonstrates its applicability to complementary metal oxide semiconductor (CMOS) sensor manufacturing. The results imply that nanostructured Ge has potential to revolutionize the sensitivity of Ge-based sensors.

Original languageEnglish
Article number2000047
Number of pages5
JournalAdvanced Optical Materials
Issue number11
Early online date29 Mar 2020
Publication statusPublished - 1 Jun 2020
MoE publication typeA1 Journal article-refereed


  • germanium
  • nanostructures
  • dry etching
  • sensors
  • near-infrared


Dive into the research topics of 'Nanostructured germanium with >99% absorption at 300-1600 nm wavelengths'. Together they form a unique fingerprint.

Cite this