We report on the detailed electrical investigation of all-inkjet-printed thin-film transistor (TFT) arrays focusing on TFT failures and their origins. The TFT arrays were manufactured on flexible polymer substrates in ambient condition without the need for cleanroom environment or inert atmosphere and at a maximum temperature of 150 °C. Alternative manufacturing processes for electronic devices such as inkjet printing suffer from lower accuracy compared to traditional microelectronic manufacturing methods. Furthermore, usually printing methods do not allow the manufacturing of electronic devices with high yield (high number of functional devices). In general, the manufacturing yield is much lower compared to the established conventional manufacturing methods based on lithography. Thus, the focus of this contribution is set on a comprehensive analysis of defective TFTs printed by inkjet technology. Based on root cause analysis, we present the defects by developing failure categories and discuss the reasons for the defects. This procedure identifies failure origins and allows the optimization of the manufacturing resulting finally to a yield improvement.

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Paradoxically more than 50 years after being used in WWII, polycrystalline PbSe technology has turned today into an emerging technology. Without any doubt one of the main facts responsible for the PbSe resurgence is a new method for processing detectors based on a Vapour Phase Deposition (VPD) technique developed at CIDA. Using this method, the first low density 2D PbSe Focal Plane Array (FPA), an x-y addressed type device, was processed on silicon. Even though the last advances have been important they are not yet enough to consider this technology as a real alternative to other uncooled technologies. To reach technical relevance and commercial interest it is obligated to integrate monolithically or hybridize the sensors with their corresponding read out electronics (ROIC). Aiming to process monolithic devices, a proper CMOS read out electronics were designed. In parallel, enabled technologies were developed for adapting the material peculiarities to the CMOS substrates. In this work, the first monolithic device of VPD PbSe is presented. Even though it is a modest 16x16 FPA with a pitch of 200 µm, it represents an important milestone, allocating polycrystalline PbSe among the major players in the short list of uncooled IR detectors. Unlike microbolometers and ferroelectrics, it is a photonic detector suitable for being used as a detector in low cost IR imagers sensitive to the MWIR band and with frame rates as high as 1000 fps. The number of applications is therefore huge, some of them specific, unique and highly demanded in the military and security fields such as sensors applied to fast imagers, Active Protection Systems or low cost seekers.

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