Polarization imaging has become a widely-applied detection technique, due to the capabilities of enhanced image contrast and object recognition. Here, we demonstrate 320 × 256 InGaAs focal plane array (FPA) integrated with superpixel-structured subwavelength aluminum grating. An extinction ratio of up to 19:1 at 1310 nm is realized, which indicates a good capability of near-infrared polarization detection. Theoretical simulation shows a fairly high extinction ratio for such superpixel structure. This difference between the actual extinction ratio and the theoretical extinction ratio is further discussed by analyzing the effects of the alignment deviation and structural parameter deviations induced during the actual process. Moreover, the imaging results show that the fabricated polarimetric InGaAs FPA presents a more obvious profile for artificial objects, compared to the conventional detector. Such FPAs integrated with superpixel-structured grating are very promising for high performance polarization imaging in the short wavelength infrared band.

A visible–extended shortwave infrared indium gallium arsenide (InGaAs) focal plane array (FPA) detector is the ideal choice for reducing the size, weight and power (SWaP) of infrared imaging systems, especially in low-light night vision and other fields that require simultaneous visible and near-infrared light detection. However, the lower quantum efficiency in the visible band has limited the extensive application of the visible–extended InGaAs FPA. Recently, a novel optical metasurface has been considered a solution for a high-performance semiconductor photoelectric device due to its highly controllable property of electromagnetic wave manipulation. Broadband Mie resonator arrays, such as nanocones and nanopillars designed with FDTD methods, were integrated on a back-illuminated InGaAs FPA as an AR metasurface. The visible–extended InGaAs detector was fabricated using substrate removal technology. The nanostructures integrated into the Vis-SWIR InGaAs detectors could realize a 10–20% enhanced quantum efficiency and an 18.8% higher FPA response throughout the wavelength range of 500–1700 nm. Compared with the traditional AR coating, nanostructure integration has advantages, such as broadband high responsivity and omnidirection antireflection, as a promising route for future Vis-SWIR InGaAs detectors with higher image quality.

Shortwave infrared polarization imaging can increase the contrast of the target to the background to improve the detection system’s recognition ability. The division of focal plane polarization indium gallium arsenide (InGaAs) focal plane array (FPA) detector is the ideal choice due to the advantages of compact structure, real-time imaging, and high stability. However, because of the mismatch between nanostructures and photosensitive pixels as well as the crosstalk among the different polarization directions, the currently reported extinction ratio (ER) of superpixel-polarization-integrated detectors cannot meet the needs of high-quality imaging. In this paper, a 1024 × 4 InGaAs FPA detector on-chip integrated with a linear polarization grating (LPG) was realized and tested. The detector displayed good performance throughout the 0.9–1.7 um band, and the ERs at 1064 nm, 1310 nm and 1550 nm reached up to 22:1, 29:1 and 46:1, respectively. For the crosstalk investigation, the optical simulation of the grating-integrated InGaAs pixel was carried out, and the limitation of the ER was calculated. The result showed that the scattering of incident light in the InP substrate led to the crosstalk. Moreover, the deviation of the actual grating morphology from the designed structure caused a further reduction in the ER.

To develop extended InGaAs photodiode focal plane arrays with large scale and small pixels, a surface passivation film with low stress is necessary. To study the surface bowing of SiN_x passivation film deposited with different conditions by inductively coupled plasma chemical vapor deposition, 2-in. InP samples were first utilized to obtain statistical results. As can be seen from the result, the bowing introduced by the passivation film is reduced to less than 10 μm when applying optimized film deposition conditions, which is a significant optimization. In the further investigation of the passivation effect on the InGaAs photodiode, Al₂O₃/SiN_x stacks were proposed as the passivation layer, and Al₂O₃ was deposited by atomic layer deposition (ALD). Results demonstrate that the photodiodes passivated by the Al₂O₃/SiN_x stacks have lower dark current density, especially at lower temperatures. At 180 K, the contribution of perimeter dark current is reduced by more than one order of magnitude. Theoretical analysis shows that the composite passivation film effectively suppresses tunneling current at 180 K.

The dark current and the photo response characteristics of extended wavelength In _0.83 Ga _0.17 As/InP photodetectors (PDs) with n-In _0.83 Ga _0.17 As absorber doped to 8×10 ¹⁵ , 7×10 ¹⁶ and 1×10 ¹⁷ cm ^-3 are investigated in an elevated temperature range of -40 to 100°C. The lightly doped PD exhibits a lower (higher) dark current than the heavily doped PD at temperatures higher (lower) than 30°C. The photocurrent, the spectral responsivity and the blackbody response voltage for the heavily doped PD rapidly decrease at temperatures higher than 30°C, while remain almost unchanged until 90°C for the lightly doped PD. The trend of the intermediately doped PD is between the two. In contrast, a consistently increasing trend of the dark noise over the whole measured temperature range are observed for three PDs. Theoretical calculations indicate such behaviors are essentially related with the temperature-dependent variation of the Shockley-Read-Hall lifetimes under different doping concentration.