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Resumen:
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Along this thesis, titled “Near Infrared detectors based on silicon supersaturated with transition metals”, we describe the research based on Ti supersaturated Si substrates, aiming to extend the photoresponse of bare Si towards photon energies lower than the bandgap at room temperature. The starting material is a crystalline Si substrate, which is Ti ion implanted in concentrations up to five orders of magnitude higher than the solid solubility limit (hence the “supersaturation” term). Later, a Nanosecond Laser Annealing (NLA) treatment is used to recover the crystal quality lost after the implantation process. When the concentration of Ti atoms is high enough, the discrete wavefunction of each impurity may overlap to form an allowed band of states between the valence and the conduction band, called the impurity band. Thus, carriers from the valence band could promote to the conduction band through the Ti impurity band by absorbing photons with energy lower than the bandgap. The purpose of the thesis is to develop a fabrication route that could integrate the Ti supersaturated Si material into a commercial CMOS Image Sensor, targeting the imaging in the Near Infrared (NIR) and Short-Wave Infrared (SWIR) ranges, that is, from 0.7 to 3.0 ?m, at room temperature. There are several fields (outdoors night vision, smart driving, food inspection, disaster management, oil spill detection, Internet of Things) that are demanding cheaper IR imaging sensors with higher resolutions. A material based on silicon, compatible with a CMOS route, could offer more competitive alternatives to what is actually available in the market. Most imaging solutions used in the NIR and SWIR range nowadays lack one or more of the next features: CMOS route compatibility (which has a direct impact on the cost), room temperature operation, fast response, high scalability (to provide resolutions, at least, of several megapixels), environmentally friendly and abundant raw materials. To date, uncooled Ge and InGaAs photodetectors are mostly used to detect photons in the SWIR range, which feature considerably higher prices per pixel than Si technologies...
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