Solution based Al/PbS and Ti-Au/PbS Schottky photodiodes for SWIR detection

Official URL: http://dx.doi.org/10.1117/12.979806

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/cm(2) illumination, 0.195 A/W responsivity and 8.19 x 10(10) 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 10(10) Jones normalized detectivity is achieved.