TY - JOUR

T1 - Quantum Size Effects in Germanium Nanocrystals and Amorphous Nanoclusters in GeSi xO y Films

AU - Gambaryan, M. P.

AU - Krivyakin, G. K.

AU - Cherkova, S. G.

AU - Stoffel, M.

AU - Rinnert, H.

AU - Vergnat, M.

AU - Volodin, V. A.

N1 - Publisher Copyright: © 2020, Pleiades Publishing, Ltd. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/3/1

Y1 - 2020/3/1

N2 - Films of nonstoichiometric germanium–silicon glasses of two types—GeOx[SiO](1 – x) and GeOx[SiO2](1 – x)—are deposited onto cold Si (001) substrates by evaporating GeO2 and SiO (or SiO2) powders simultaneously in high vacuum. Film samples in their initial (as-deposited) state and after being annealed at 550 and 650°C for 1 h are investigated using IR and Raman spectroscopies and electron microscopy, and their photoluminescence (PL) is studied as well. Raman spectroscopy shows that, in contrast to the initial GeO[SiO2] film, the initial GeO[SiO] one contains clusters of amorphous germanium, their size being ~3 nm, as found by electron microscopy. The presence of Si–O, Ge–O, and Si–O–Ge bonds in the films is established by IR spectroscopy. Clusters of amorphous germanium are found in both films after annealing at 550°C, while germanium nanocrystals are formed in the films subjected to annealing at 650°C. For the initial films, a broad band with a maximum at 1050 nm is registered in their low-temperature PL spectra, which may originate from such defects as oxygen vacancies and overstoichiometric germanium atoms. Annealing causes structural changes in the films and affects their PL behavior. The films containing germanium nanoclusters give rise to PL with a maximum at 1400–1600 nm, with the defect-related signal being diminished. The temperature dependence of PL intensity exhibits a decreasing behavior, but PL is observed to temperatures as high as 200 K. The contribution of germanium nanocrystals formed at the annealing stage to PL is discussed.

AB - Films of nonstoichiometric germanium–silicon glasses of two types—GeOx[SiO](1 – x) and GeOx[SiO2](1 – x)—are deposited onto cold Si (001) substrates by evaporating GeO2 and SiO (or SiO2) powders simultaneously in high vacuum. Film samples in their initial (as-deposited) state and after being annealed at 550 and 650°C for 1 h are investigated using IR and Raman spectroscopies and electron microscopy, and their photoluminescence (PL) is studied as well. Raman spectroscopy shows that, in contrast to the initial GeO[SiO2] film, the initial GeO[SiO] one contains clusters of amorphous germanium, their size being ~3 nm, as found by electron microscopy. The presence of Si–O, Ge–O, and Si–O–Ge bonds in the films is established by IR spectroscopy. Clusters of amorphous germanium are found in both films after annealing at 550°C, while germanium nanocrystals are formed in the films subjected to annealing at 650°C. For the initial films, a broad band with a maximum at 1050 nm is registered in their low-temperature PL spectra, which may originate from such defects as oxygen vacancies and overstoichiometric germanium atoms. Annealing causes structural changes in the films and affects their PL behavior. The films containing germanium nanoclusters give rise to PL with a maximum at 1400–1600 nm, with the defect-related signal being diminished. The temperature dependence of PL intensity exhibits a decreasing behavior, but PL is observed to temperatures as high as 200 K. The contribution of germanium nanocrystals formed at the annealing stage to PL is discussed.

KW - germanium nanoclusters

KW - germanium–silicon glasses

KW - photoluminescence

KW - quantum size effect

KW - RAMAN-SCATTERING

KW - germanium-silicon glasses

KW - SILICON

KW - OPTICAL-PROPERTIES

KW - VISIBLE PHOTOLUMINESCENCE

KW - GE NANOCRYSTALS

KW - ABSORPTION

UR - http://www.scopus.com/inward/record.url?scp=85082389976&partnerID=8YFLogxK

U2 - 10.1134/S1063783420030105

DO - 10.1134/S1063783420030105

M3 - Article

AN - SCOPUS:85082389976

VL - 62

SP - 492

EP - 498

JO - Physics of the Solid State

JF - Physics of the Solid State

SN - 1063-7834

IS - 3

ER -