High performance short wavelength infrared focal plane arrays

Download
2017
Çırçır, Kübra
Short Wavelength Infrared (SWIR) band is desirable for many applications such as night vision, spectroscopy and hyperspectral imaging. Indium Gallium Arsenide (In0.53Ga0.47As) is a suitable material for SWIR photodetectors. This thesis focuses on the investigation of the pixel characteristics of a 15 µm pitch large format (640x512) focal plane array (FPA) with In0.53Ga0.47As absorber and Al0.52In0.48As p-type cap layers as an alternative to the conventional In0.53Ga0.47As detectors utilizing InP as the p-cap layer. The FPA pixels were fabricated in the mesa structure in order to provide a comparison to the conventional planar type pixel arrangement. The dark current density of the FPA pixels was measured as 96 µA/cm2 at 290 K. In order to determine the dominant dark current component, a model including diffusion, generation-recombination (G-R) and shunt currents is adopted. The results of fitting indicate that large area (≥ 75x75 µm2) pixels display bulk G-R dominated dark current behavior with the dark current density independent of the pixel dimensions. The trap characteristics extracted from fitting of G-R lifetime curve display an activation energy of 0.17 eV with respect to the intrinsic level (Ei), which is in reasonable agreement with the Deep Level Transient Spectroscopy (DLTS) characterization results. On the other hand, as pixel-pitch decreases to 15 µm, surface related G-R component becomes the dominant dark current component. Therefore, the above mentioned trap density should be decreased and the passivation of the mesa sidewalls should be improved in order to improve the mesa-type FPA pixel performance. 
Citation Formats
K. Çırçır, “High performance short wavelength infrared focal plane arrays,” M.S. - Master of Science, Middle East Technical University, 2017.