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. 2023 Mar 20;13(14):9154-9167.
doi: 10.1039/d3ra00805c.

Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation

Mohamed A Nawwar  1 , Magdy S Abo Ghazala  1 , Lobna M Sharaf El-Deen  1 , Badawi Anis  2 , Abdelhamid El-Shaer  3 , Ahmed Mourtada Elseman  4 , Mohamed M Rashad  4 , Abd El-Hady B Kashyout  5
Affiliations

Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation

Mohamed A Nawwar et al. RSC Adv. .

Erratum in

Abstract

GeSn compounds have made many interesting contributions in photodetectors (PDs) over the last ten years, as they have a detection limit in the NIR and mid-IR region. Sn incorporation in Ge alters the cut off wavelength. In the present article, p-i-n structures based on GeSn junctions were fabricated to serve as PDs. Arsine (As) is incorporated to develop n-GeSn compounds via a metal induced crystallization (MIC) process followed by i-GeSn on p-Si wafers. The impact of As and Sn doping on the strain characteristics of GeSn has been studied with high resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy analyses. The direct transitions and tuning of their band energies have been investigated using diffuse reflectance UV-vis spectroscopy and photoluminescence (PL). The barrier height and spectral responsivity have been controlled with incorporation of As. Variation of As incorporation into GeSn Compounds shifted the Raman peak and hence affected the strain in the Ge network. UV-vis spectroscopy showed that the direct transition energies are lowered as the Ge-As bonding increases as illustrated in Raman spectroscopy investigations. PL and UV-vis spectroscopy of annealed heterostructures at 500 °C showed that there are many transition peaks from the UV to the NIR region as result of oxygen vacancies in the Ge network. The calculated diode parameters showed that As incorporation leads to an increase of the height barrier and thus dark current. Spectral response measurements show that the prepared heterojunctions have spectral responses in near UV and NIR regions that gives them opportunities in UV and NIR photodetection-applications.

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Conflict of interest statement

The authors declare no competing interests or non-financial interests.

Figures

Fig. 1
Fig. 1. Formation of GeSn based p–i–n diodes via metal induced crystallization (MIC).
Fig. 2
Fig. 2. (a–c) Low and HRTEM images of a prepared Ge/Sn/Ge/As configuration on p-Si substrate after MIC, (d) selected area electron diffraction, (e) EDX spectra, and (f) the atomic and weight percentage of the elements forming the sample.
Fig. 3
Fig. 3. Elemental mapping analysis of prepared Ge/Sn/Ge/As configuration annealed on p-Si.
Fig. 4
Fig. 4. XRD patterns of (a) Si/Sn/Ge/As and (b) Ge/Sn/Ge/As configurations on p-Si annealed at 500 °C.
Fig. 5
Fig. 5. Raman shifting of the prepared heterostructures (a) Si/Sn/Ge/As on p-Si, (b) Si/Sn/Ge/Sn/As on p-Si, (c) Ge/Sn/Ge/As on p-Si and (d) Ge/Sn/Ge/Sn/As on p-Si.
Fig. 6
Fig. 6. Sn solubility in Ge rather than Si.
Fig. 7
Fig. 7. (khν)2versus hν plot of the prepared heterostructures.
Fig. 8
Fig. 8. Deep As incorporation inside Ge network during annealing process.
Fig. 9
Fig. 9. (a) Indirect to direct transition band gap due to Sn and As incorporation in strained Ge network. (b) Photoluminescence spectra of the prepared heterostructures.
Fig. 10
Fig. 10. I–V characteristic plot of the prepared heterostructures in ±5 V forward and reverse biasing (a) Si/Sn/Ge/As on p-Si, (b) Si/Sn/Ge/Sn/As on p-Si, (c) Ge/Sn/Ge/As on p-Si, and (d) Ge/Sn/Ge/Sn/As on p-Si.
Fig. 11
Fig. 11. The current density in logarithmic scale versus voltage of the prepared p–i–n junctions.
Fig. 12
Fig. 12. Plot of ln(I) versus V for the prepared junctions. (a) Si/Sn/Ge/As, (b) Si/Sn/Ge/Sn/As, (c) Ge/Sn/Ge/As, and (d) Ge/Sn/Ge/Sn/As on p-Si.
Fig. 13
Fig. 13. Responsivity of the prepared heterojunctions in (300 nm–1200 nm) spectral range.
Fig. 14
Fig. 14. Responsivity of the prepared heterojunctions in (800 nm–1600 nm) spectral range and cut off edge.
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