Silicon
and PbS colloidal quantum dot heterojunction photodetectors
combine the advantages of the Si device and PbS CQDs, presenting a
promising strategy for infrared light detecting. However, the construction
of a high-quality CQDs:Si heterojunction remains a challenge. In this
work, we introduce an inverted structure photodetector based on n-type
Si and p-type PbS CQDs. Compared with the existing normal structure
photodetector with p-type Si and n-type PbS CQDs, it has a lower energy
band offset that provides more efficient charge extraction for the
device. With the help of Si wafer surface passivation and the Si doping
density optimization, the device delivers a high detectivity of 1.47
× 1011 Jones at 1540 nm without working bias, achieving
the best performance in Si/PbS photodetectors in this region now.
This work provides a new strategy to fabricate low-cost high-performance
PbS CQDs photodetectors compatible with silicon arrays.
We report the demonstration of a normal-incidence p-i-n germanium-tin (
Ge
0.951
Sn
0.049
) photodetector on silicon-on-insulator substrate for 2 μm wavelength application. The DC and RF characteristics of the devices have been characterized. A dark current density under
−
1
V
bias of approximately
125
mA/
cm
2
is achieved at room temperature, and the optical responsivity of 14 mA/W is realized for illumination wavelength of 2 μm under
−
1
V
reverse bias. In addition, a 3 dB bandwidth (
f
3
dB
) of around 30 GHz is achieved at
−
3
V
, which is the highest reported value among all group III–V and group IV photodetectors working in the 2 μm wavelength range. This work illustrates that a GeSn photodetector has great prospects in 2 μm wavelength optical communication.
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