Interplay of strain and intermixing effects on direct-bandgap optical transition in strained Ge-on-Si under thermal annealing

Chulwon Lee, Yang Seok Yoo, Bugeun Ki, Min Ho Jang, Seung Hyuk Lim, Hyun Gyu Song, Jong Hoi Cho, Jungwoo Oh, Yong Hoon Cho

Research output: Contribution to journalArticle

Abstract

The influence of thermal annealing on the properties of germanium grown on silicon (Ge-on-Si) has been investigated. Depth dependencies of strain and photoluminescence (PL) were compared for as-grown and annealed Ge-on-Si samples to investigate how intermixing affects the optical properties of Ge-on-Si. The tensile strain on thermally annealed Ge-on-Si increases at the deeper region, while the PL wavelength becomes shorter. This unexpected blue-shift is attributed to Si interdiffusion at the interface, which is confirmed by energy dispersive X-ray spectroscopy and micro-Raman experiments. Not only Γ- and L-valley emissions but also Δ2-valley related emission could be found from the PL spectra, showing a possibility of carrier escape from Γ valley. Temperature-dependent PL analysis reveals that the thermal activation energy of Γ-valley emission increases at the proximity of the Ge/Si interface. By comparing the PL peak energies and their activation energies, both SiGe intermixing and shallow defect levels are found to be responsible for the activation energy increase and consequent efficiency reduction at the Ge/Si interface. These results provide an in-depth understanding of the influence of strain and Si intermixing on the direct-bandgap optical transition in thermally annealed Ge-on-Si.

Original languageEnglish
Article number11709
JournalScientific reports
Volume9
Issue number1
DOIs
Publication statusPublished - 2019 Dec 1

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optical transition
germanium
valleys
photoluminescence
annealing
silicon
activation energy
blue shift
escape
proximity
optical properties
energy
defects
wavelengths
spectroscopy
x rays
temperature

All Science Journal Classification (ASJC) codes

  • General

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Lee, Chulwon ; Yoo, Yang Seok ; Ki, Bugeun ; Jang, Min Ho ; Lim, Seung Hyuk ; Song, Hyun Gyu ; Cho, Jong Hoi ; Oh, Jungwoo ; Cho, Yong Hoon. / Interplay of strain and intermixing effects on direct-bandgap optical transition in strained Ge-on-Si under thermal annealing. In: Scientific reports. 2019 ; Vol. 9, No. 1.
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abstract = "The influence of thermal annealing on the properties of germanium grown on silicon (Ge-on-Si) has been investigated. Depth dependencies of strain and photoluminescence (PL) were compared for as-grown and annealed Ge-on-Si samples to investigate how intermixing affects the optical properties of Ge-on-Si. The tensile strain on thermally annealed Ge-on-Si increases at the deeper region, while the PL wavelength becomes shorter. This unexpected blue-shift is attributed to Si interdiffusion at the interface, which is confirmed by energy dispersive X-ray spectroscopy and micro-Raman experiments. Not only Γ- and L-valley emissions but also Δ2-valley related emission could be found from the PL spectra, showing a possibility of carrier escape from Γ valley. Temperature-dependent PL analysis reveals that the thermal activation energy of Γ-valley emission increases at the proximity of the Ge/Si interface. By comparing the PL peak energies and their activation energies, both SiGe intermixing and shallow defect levels are found to be responsible for the activation energy increase and consequent efficiency reduction at the Ge/Si interface. These results provide an in-depth understanding of the influence of strain and Si intermixing on the direct-bandgap optical transition in thermally annealed Ge-on-Si.",
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Interplay of strain and intermixing effects on direct-bandgap optical transition in strained Ge-on-Si under thermal annealing. / Lee, Chulwon; Yoo, Yang Seok; Ki, Bugeun; Jang, Min Ho; Lim, Seung Hyuk; Song, Hyun Gyu; Cho, Jong Hoi; Oh, Jungwoo; Cho, Yong Hoon.

In: Scientific reports, Vol. 9, No. 1, 11709, 01.12.2019.

Research output: Contribution to journalArticle

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AU - Lee, Chulwon

AU - Yoo, Yang Seok

AU - Ki, Bugeun

AU - Jang, Min Ho

AU - Lim, Seung Hyuk

AU - Song, Hyun Gyu

AU - Cho, Jong Hoi

AU - Oh, Jungwoo

AU - Cho, Yong Hoon

PY - 2019/12/1

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N2 - The influence of thermal annealing on the properties of germanium grown on silicon (Ge-on-Si) has been investigated. Depth dependencies of strain and photoluminescence (PL) were compared for as-grown and annealed Ge-on-Si samples to investigate how intermixing affects the optical properties of Ge-on-Si. The tensile strain on thermally annealed Ge-on-Si increases at the deeper region, while the PL wavelength becomes shorter. This unexpected blue-shift is attributed to Si interdiffusion at the interface, which is confirmed by energy dispersive X-ray spectroscopy and micro-Raman experiments. Not only Γ- and L-valley emissions but also Δ2-valley related emission could be found from the PL spectra, showing a possibility of carrier escape from Γ valley. Temperature-dependent PL analysis reveals that the thermal activation energy of Γ-valley emission increases at the proximity of the Ge/Si interface. By comparing the PL peak energies and their activation energies, both SiGe intermixing and shallow defect levels are found to be responsible for the activation energy increase and consequent efficiency reduction at the Ge/Si interface. These results provide an in-depth understanding of the influence of strain and Si intermixing on the direct-bandgap optical transition in thermally annealed Ge-on-Si.

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