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Passivation of Detector‐Grade Float Zone Silicon with Atomic Layer Deposited Aluminum Oxide
Author(s) -
Ott Jennifer,
Pasanen Toni P.,
Repo Päivikki,
Seppänen Heli,
Vähänissi Ville,
Savin Hele
Publication year - 2019
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900309
Subject(s) - passivation , materials science , silicon , annealing (glass) , electrical resistivity and conductivity , oxide , forming gas , aluminium , doping , analytical chemistry (journal) , metallurgy , optoelectronics , layer (electronics) , nanotechnology , chemistry , electrical engineering , engineering , chromatography
Silicon radiation and particle detectors are traditionally passivated with thermal silicon dioxide. It has been shown that aluminum oxide (Al 2 O 3 ) films provide better surface passivation due to their high negative charge, but studies on Al 2 O 3 surface passivation are usually performed on low‐resistivity substrates. Herein, the passivation of high‐resistivity, detector‐grade float zone silicon (FZ‐Si) with Al 2 O 3 is studied, with a specific emphasis on the effect of post‐annealing temperature on carrier lifetimes and film properties. It is confirmed that Al 2 O 3 provides excellent surface passivation also on high‐resistivity FZ‐Si substrates, with a low interface defect density of around (2–4) × 10 11 cm −2 eV −1 and a high negative oxide charge of 1 × 10 12 to 3 × 10 12 q cm −2 , when post‐annealed at temperatures of up to 450–500 °C. In addition, high‐resistivity samples are studied for the phenomenon of bulk lifetime degradation occurring at typical post‐annealing or metal sintering temperatures, which has been reported for low‐resistivity FZ‐Si. At post‐annealing temperatures of >500 °C, reduced bulk lifetimes are observed if the substrates did not receive high‐temperature treatment prior to surface passivation. Furthermore, it is noticed that n‐type samples exhibit lower bulk lifetimes even when a high‐temperature treatment is performed, which indicates a connection between FZ‐Si bulk lifetime degradation and doping type.