GaAs-Based p-i-n Narrow Bandpass 850 nm IR Photodetector With a p-AlGaAs Filter Layer

GaAs-based p-i-n 850 nm infrared photodetectors with a narrow bandpass characteristic were successfully fabricated and demonstrated by epitaxial growth technology. The photo to dark current ratios of the fabricated PDs were
$1.76\times10$
⁷
and
$2.08\times10$
³
at 0 and −5 V, respectively. It can be seen clearly that our fabricated PDs can achieve a very steeply and rapidly falling cut-off bandpass characteristic by inserting a p-Al
_0.1
Ga
_0.9
As filter layer. The full width at half maximum of the photo response was only 65.9 nm. Then, the peak responsivity value of the fabricated PDs occurred at 855 nm was 0.49 A/W with a quantum efficiency of 71.2% at −1 V. Moreover, the low frequency noise of the fabricated PDs was dominated by 1/f-type noise. And, the best detectivity was calculated to be
$1.17\times10$
¹³
cmHz
^0.5
W
⁻¹
at a bias voltage of 0 V.