Performance of low dark current InGaAs shortwave infrared detector

In x Ga 1-x As ternary compound is suitable for detector applications in the shortwave infrared (1-3 μm) band. The alloy In 0.53 Ga 0.47 As is lattice-matched to InP substrate, which leads to high quality epitaxial layers. Consistently the In 0.53 Ga 0.47 As detector shows low dark current density and high detectivity at room temperature with wavelength response between 0.9 and 1.7 μm. In this paper, planar-type 24×1 linear InGaAs detector arrays with guard-ring structure were designed and fabricated based on n-i-n + type InP/In 0.53 Ga 0.47 As/InP epitaxial structure by sealed-ampoule diffusion method. At first the dark current density is about 30~60 nA/cm 2 at -0.1 V at room temperature. After modifications to the detector design and processing, the dark current density reduces to 2~9 nA/cm 2 at -0.1 V at 293 K. The ideality factors simulated from I-V curves come close to 1 and less than the factors of previous detectors, which indicates that the dark current is dominated by diffusion current, while the generation-recombination current exhibits in the previous detectors. At the temperature of 293 K, the R 0 A of the detector reaches more than 1×10 7 Ω·cm 2 , the relative spectral response is in the range of 0.9 μm to 1.68 μm, the mean peak responsivity is 1.2 A/W and the mean peak detectivity is more than 3.0×10 12 cm·Hz 1/2 /W.