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This thesis makes a significant contribution to the development of cheaper Si-based Infrared detectors, operating at room temperature. In particular, the work is focused in the integration of the Ti supersaturated Si material into a CMOS Image Sensor route, the technology of choice for imaging nowadays due to its low-cost and high resolution. First, the material is fabricated using ion implantation of Ti atoms at high concentrations. Afterwards, the crystallinity is recovered by means of a pulsed laser process. The material is used to fabricate planar photodiodes, which are later characterized using current-voltage and quantum efficiency measurements. The prototypes showed improved sub-bandgap responsivity up to 0.45 eV at room temperature. The work is further supported by a collaboration with STMicroelectronics, where the supersaturated material was integrated into CMOS-based sensors at industry level. The results show that Ti supersaturated Si is compatible in terms of contamination, process integration and uniformity. The devices showed similar performance to non-implanted devices in the visible region. This fact leaves the door open for further integration of supersaturated materials into CMOS Image Sensors.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
Think about any day in your life. How many of our possessions contain, at least, one microchip that are made of semiconductors? Semiconductors are the enablers of our modern society, being silicon the most important of them. There are many things that can be done with Si chips. Unfortunately, detecting infrared rays, at least at room temperature, is not one of them. In this chapter, we explore the current infrared sensing technology and their limitations. Then, we introduce the concept of supersaturated materials, and how it could be a potential solution for getting faster, cheaper, and more environmentally friendly infrared detectors, based on Si, and operating at room-temperature.
Daniel Montero Álvarez

Chapter 2. Experimental Techniques

Abstract
This section deals with the experimental techniques that have been used during the thesis. It covers several areas, from material to device preparation and characterisation. At each subsection, we briefly describe an experimental technique, explaining also its utility in our research.
Daniel Montero Álvarez

Chapter 3. Results: NLA Using a Short Pulse Duration KrF Laser

Abstract
This chapter describes the research performed on samples annealed with the KrF laser from IPG Photonics (USA), which features a short pulse duration of 25 ns, with a wavelength of 248 nm. All the samples analysed in this chapter are based on 50.8 mm wafers and have been implanted in the Faculty of Physics, using the available ion implanter belonging to CAI Técnicas Físicas. We also describe the fabrication process of the first prototypes of micro photodiodes, as well as their optical and electrical characterization, where we demonstrate the compatibility of the Ti supersaturated material with devices in the microscale.
Daniel Montero Álvarez

Chapter 4. Results: NLA Using a Long Pulse Duration XeCl Laser

Abstract
This chapter describes the research done on samples Ti implanted in our facilities at UCM, but laser annealed with the XeCl excimer laser described in Sect. 2.2.1, belonging to SCREEN-LASSE (Paris). This laser features a wavelength of 308 nm, a pulse duration of 150 ns at FWHM and a laser spot of 10 × 10 mm2, which allows for full die exposure processes. A full design of experiment was performed using the new laser, where samples were characterized using electrical and quantum efficiency measurements. Samples were fabricated with different supersaturation conditions, by sweeping the Ti implantation dose and laser fluence. The goal is to find the best candidate in terms of quantum efficiency in the sub-bandgap region (the SWIR range).
Daniel Montero Álvarez

Chapter 5. Results: Integrating the Supersaturated Material in a CMOS Pixel Matrix

Abstract
The information contained in this chapter is the result of the collaboration between the UCM and STMicroelectronics, through an internship financed by the Spanish Ministry of Science and Universities, under grant no. EEBB-I-17-12315. The internship took place between September 1st of 2017 and March 4th of 2018. The aim of the collaboration is to integrate the Ti supersaturated material into a precommercial CMOS Image Sensor route, aiming to explore the viability of this material and the integration challenges that can arise during the fabrication and characterization process of the Focal Plane Array sensors. Most of the chapter is dedicated to the material characterization, although at the end the electrooptical characterisation of Ti implanted devices will be shown and discussed.
Daniel Montero Álvarez

Chapter 6. Final Considerations

Abstract
Along this chapter, we briefly describe the main conclusions derived from our research. This thesis started as the natural continuation of the thesis of E. García-Hemme, where he demonstrated that Ti supersaturated Si layers on macroscale devices, based on n-type substrates, could exhibit sub-bandgap photoresponse at room temperature, in the SWIR range, down to around 0.45 eV (3 μm). In the present work, we extend the research towards a possible industrialization of the supersaturated material. In a first step, we fabricated the first micrometrical prototypes, which showed improved sub-bandgap photoresponse. Later, we establish a collaboration with STMicroelectronics, where we could demonstrate that Ti supersaturated Si is compatible with a CMOS Image Sensor route. This fact paves the way to continue the research in collaboration with the industry.
Daniel Montero Álvarez

Chapter 7. Future Progress

Abstract
The results derived from this thesis (briefly discussed in the previous chapter) leave the door open for further development and optimisation in several branches, which are briefly described in this chapter.
Daniel Montero Álvarez

Backmatter

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