Effects of high-temperature thermal annealing on GeSn thin-film material and photodetector operating at 2 µm

•Ordered nanopatterns are formed on the surface of GeSn from high-temperature annealing (~700 °C).•Structural and optical properties of GeSn films before and after rapid thermal annealing are reported.•An increased photocurrent (>200%) is observed for the GeSn photodetector at an annealing temper...

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Bibliographic Details
Published in:Journal of alloys and compounds 2021-08, Vol.872, p.159696, Article 159696
Main Authors: Wu, Shaoteng, Son, Bongkwon, Zhang, Lin, Chen, Qimiao, Zhou, Hao, Goh, Simon Chun Kiat, Tan, Chuan Seng
Format: Article
Language:English
Subjects:
Annealing
Crystal structure
Crystals
Dark current
GeSn alloy
High temperature
Infrared photodetector
Intermetallic compounds
Nanopattern
Photoelectric effect
Photoelectric emission
Photometers
Secondary ion mass spectrometry
Structural property
Temperature
Thermal stability
Tin
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Summary:•Ordered nanopatterns are formed on the surface of GeSn from high-temperature annealing (~700 °C).•Structural and optical properties of GeSn films before and after rapid thermal annealing are reported.•An increased photocurrent (>200%) is observed for the GeSn photodetector at an annealing temperature of 550 °C at 2-µm wavelength. Here, we explore the thermal stability of GeSn epilayers with varying Sn contents (3–10%) at an annealing temperature ranging from 300° to 750°C. It is found that ordered nanopatterns are formed on the surface of GeSn with Sn content of 8% without excessive Sn precipitation after thermal annealing at 700 °C. Despite being annealed at high temperatures, the GeSn maintains its crystal structure, which is confirmed by the X-ray Diffraction (XRD), Raman spectrum, and secondary-ion mass spectrometry (SIMS). The corresponding photocurrents of the photodetectors at the wavelength of 2 µm also indicate the crystal quality of the GeSn alloys does not deteriorate significantly after high-temperature annealing (675–700 °C). Meanwhile, the decrease of dark current with the enhancement of Ip/Id ratio (on-off ratio) indicates the improvement of detectivity of the photodetector due to the annealing process. Furthermore, the annealing temperature is optimized to 550 °C to achieve 200% enhancement of photocurrents of the GeSn photodetectors operated at 2 µm.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2021.159696