In this work, PbS Colloidal Quantum Dots (CQD) based photodiodes are realized on both silicon substrates and on the replicas of the ROICs in order to demonstrate fully integrated FPAs. Careful optimization of PbS CQD film formation and ligand exchange process, together with optimization of IC integrable process steps resulted in high performance, monolithically integrable photodiodes. High quantum efficiencies such as 32% is achieved for photodiodes on Si substrates and high responsivities up to 5,73 A/W is achieved for photodiodes on ROIC replicas. Also these detectors achieved very high normalized detectivities such as; 1.36 x 1011 Jones and 1.42 x 1012 Jones under 1V and 2V reverse bias respectively, which is close to conventional InGaAS SWIR detectors.
In this work, PbS colloidal quantum dot based photodiodes are realized that is compatible for integration to read out electronics. Schottky photodiode topology is selected to implement PbS quantum dots as photodetector because of its fast response and moderate sensitivity. The device is formed from Indium tin oxide (ITO) anode, the photosensitive PbS layer and a schottky contact formed of both aluminum or titanium and gold stack. Ligand exchange processes optimized in order to replace long capping ligands of PbS QDs with shorter ones. Layer by layer deposition method is applied to form pinhole free PbS CQD films. For Al/PbS samples rectification ratios greater than 100 is achieved for ±2 V bias voltages. At 2V reverse bias and under 5mW/cm2 illumination, 0.195 A/W responsivity and 8.19 x 1010 Jones normalized detectivity is achieved. For Ti-Au/PbS samples, rectification ratio greater than 250 is achieved for ±2 V bias voltages. At 3V reverse bias, 0.667 A/W responsivity, 53.3 % quantum efficiency and 2,12 x 1010 Jones normalized detectivity is achieved.
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