Yiding Lin, Kwang Hong Lee, Shuyu Bao, Xin Guo, Hong Wang, Jurgen Michel, Chuan Seng Tan, "High-efficiency normal-incidence vertical p-i-n photodetectors on a germanium-on-insulator platform," Photonics Res. 5, 702 (2017)

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- Photonics Research
- Vol. 5, Issue 6, 702 (2017)

Fig. 1. Schematic of bonding and layer transfer technique for GOI p - i - n structure fabrication.

Fig. 2. (a) SIMS doping profiles of B and As in Ge vertical p - i - n structure. Inset shows a corresponding cross-sectional TEM image of the fabricated GOI p - i - n structure at bonding interface. (b) HRXRD (004) 2 θ − ω scan of as-grown Ge-on-Si and GOI p - i - n structure with that of bulk Ge as reference. Tensile strain of ∼ 0.15 % for the Ge layer in the GOI was obtained. The values in the plot correspond to the respective peak 2 θ − ω angles.

Fig. 3. (a) Cross-sectional schematic of a GOI vertical p - i - n photodetector (PD) and (b) its optical microscope image with a mesa diameter of 80 μm. The FESEM image above presents the cross-sectional view of the detector along the green solid line across the mesa.

Fig. 4. (a) Dark current density-voltage characteristic of GOI vertical p - i - n PDs with different mesa diameters. (b) Temperature-dependent study on dark current of GOI vertical p - i - n PD at − 0.5 V .

Fig. 5. (a) Photocurrent of a GOI vertical p - i - n PD (mesa diameter of 250 μm) as a function of applied bias, with its dark I-V characteristic as a reference. Inset shows the corresponding measurement configuration. (b) Optical responsivity spectrum of GOI vertical p - i - n PD across C- and L- telecommunication bands. Inset shows the corresponding first-order derivative of the responsivity spectrum.
![Performance comparison of Ge-based PDs. i-Ge thicknesses for the corresponding Ge-on-Si and Ge-on-SOI devices (without AR coating) in the references (numbers in square brackets) were indicated. The i-Ge thicknesses for GOI PDs were not indicated due to their discrepant configurations (interdigitated lateral p-i-n [19] and waveguide-integrated [21]).](/Images/icon/loading.gif)
Fig. 6. Performance comparison of Ge-based PDs. i -Ge thicknesses for the corresponding Ge-on-Si and Ge-on-SOI devices (without AR coating) in the references (numbers in square brackets) were indicated. The i -Ge thicknesses for GOI PDs were not indicated due to their discrepant configurations (interdigitated lateral p - i - n [19] and waveguide-integrated [21]).

Fig. 7. (a) Frequency response of GOI vertical p - i - n PD (mesa diameter of 60 μm) at − 2 V . Inset shows device series resistance extracted from I-V characteristics. (b) Calculated 3 dB bandwidth of GOI vertical p - i - n detector (R s = 30 Ω ) with respect to its mesa diameter (red solid line). The dashed line represents the corresponding carrier transit-limited bandwidth. Inset shows linear interpolation of device capacitances at − 2 V for de-coupling of junction and parasitic capacitances. (c) Calculated 3 dB bandwidth of the PD with mesa diameter of 10 μm with respect to i -Ge thickness.

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