The extended InGaAs short wavelength infrared (SWIR) detector covers 1.0-2.5 μm wavelength, which plays an important role in weather forecast, resource observation, low light level systems, and astronomical observation and so on. In order to fabricate the high performance extended InGaAs detector, materials structure and parameters were characterized with Scanning Capacitance Microscopy (SCM), Scanning Spreading Resistance Microscopy (SSRM), the spreading of minority carriers and lattice quality were obtained. Mesa etching process, etching damage restoration technique and low temperature passivation technique were used in the fabrication of the extended InGaAs detector. The improvement of material structure and device process was studied by fabricating and measuring different perimeter-to-area (P/A) photodiodes and singledevice, respectively. The dark current density of the extended InGaAs detector obviously was reduced, about 2 nA/cm<sup>2</sup> at 170 K. The 512×256 FPAs were fabricated, the peak detectivity and the quantum efficiency of which are 5×10<sup>11</sup> cmHz<sup>1/2</sup>/W and 80%, respectively. The staring image yielded of the 512×256 FPAs is shown, which demonstrates very good imaging quality.
In<sub>x</sub>Ga<sub>1-x</sub>As ternary compound is suitable for detection in the shortwave infrared (1-3μm) band. The alloy In<sub>0.53</sub>Ga<sub>0.47</sub>As is lattice-matched to InP substrate and has a wavelength response between 0.9μm to 1.7μm at room temperature. The increase of indium composition can extend the wavelength response to longer infrared wave. With the Indium content 0.83, the cutoff wavelength can be extended to 2.6μm. In this paper, we reported the performance of 64x64 pixels mesa-type back-illuminated extended wavelength InGaAs detector arrays. The mesa type detectors were fabricated by ICP etching, side-wall and surface passivation by ICPCVD (inductively coupled plasma chemical vapor deposition) based on the MBE-grown p-i-n In<sub>0.83</sub>Al<sub>0.17</sub>As/In<sub>0.83</sub>Ga<sub>0.17</sub>As/In<sub>x</sub>Al<sub>1-x</sub>As/InP epitaxial materials. The I-V characteristics and electro-optical performances of these detectors at different temperatures were measured, and the properties such as dark current, response spectra, responsivity, detectivity were analyzed. The results indicate that the dark current of In<sub>0.83</sub>Ga<sub>0.17</sub>As photodiodes decreases with decreasing temperature, varying from 4×10<sup>-4</sup>A/cm<sup>2</sup> at 290K to 1.7×10<sup>-8</sup>A/cm<sup>2</sup> at 180K. The spectral response showed slightly blue shift while the detectors were cooling down, and the cut-off wavelength is 2.57μm at room temperature and 2.43μm at 200K, respectively. The dark current density is 115nA/cm<sup>2</sup> at 200K and -10mV bias voltage. The peak detectivity is 6.08E11cmHz<sup>1/2</sup>W<sup>-1</sup>.
Extended wavelength InGaAs photodiodes in 1.0~2.5μm spectral rang based on two types of material structures were investigated systematically. The first type InGaAs photodiode, marked by sample 1#, was fabricated using MOCVD epitaxial materials with P-i-N structure. The second type InGaAs photodiodes, marked by sample 2#, was fabricated using MBE epitaxial materials with P-i-N structure. The two types of photodiodes were fabricated by mesa etching technique, side-wall and surface passivation film. Dark current and voltage curves were measured by semiconductor parameters analyzer at different temperature, and dark current characteristics were analyzed using different perimeter to area method. The mechanism of the devices has been analysed. Polarization microscopy and conductive atomic force microscopy (c-AFM) have been used to investigate the local conductivity of the photodiodes’ sensitive area. Combining the optical and c-AFM micrographs with dark current characteristics, we intended to characterize the relationships of the leak current and the defect. The results indicate that sample 1# has relative much more leak defects than that of sample 2#, and thus the dark current sample 1# is higher than that of sample 2# and. The defects are generated at the body of material and spread to the surface, and these defects cause very high dark current of sample 1#.
In<sub>x</sub>Ga<sub>1-x</sub>As ternary compound is suitable for detector applications in the shortwave infrared (1-3 μm) band. In this paper,
we reported on mesa type and planar type extended wavelength InGaAs detector arrays. The photo response
performances of these detector arrays were investigated. The blackbody responsivities (R<i><sub>bb</sub></i>) of these detectors at different
temperatures were measured, and the results showed that the Rbb of planar type arrays was higher than that of the
conventionally passivated mesa type, but the mesa arrays fabricated by improved passivating technique has the highest
responsivity. The reason of the R<i><sub>bb</sub></i> difference between the arrays was analyzed, and it is found that the difference mostly
comes from the minority carrier lifetime, which is related to the device structures and fabrication processes. With the
optimized fabrication processes the mesa type arrays can obtain higher blackbody responsivity even more than the planar