Electron devices Lab


The research activities of the group are related to the analysis of the operating principles of solid-state electronic devices, to their design and fabrication as well as to the testing of the obtained prototypes. Among the various electronic components, two are the main categories investigated: i) devices for storing information based on CMOS technology and ii) optoelectronic devices based on organic semiconductor materials. The first class of devices is one of the leading sectors of the semiconductor industry today, while the second offers attractive possibilities for new technological development in a large number of electronic applications.
  • Memory Devices:
    The research addresses the technologies of non-volatile storage that guarantee to preserve the stored data even in the absence of electrical supplies. The research activities are focusing both on Flash technology, which is the main technology for storing non-volatile solid state since decades, and on emerging technologies that could carve out a future in this market sector. Concerning the Flash memory, research started from the 130-nm technology nodes down to the current 16-nm, dealing with experimental characterization, modeling studies and numerical simulations to address the main physical phenomena that have emerged to impact performance and reliability, such as the random telegraph noise, the noise of programming, the release of charge from the dielectric and the statistical variability arising from the granularity of the electric charge. Among the emerging technologies investigated by the group, a major role is played by the phase change memories (PCM) and resistive memories (ReRAM), which are the subject of our activity since their initial proposal. The research on these technologies involves the study at a physics level of the microscopic structure of the materials used as a storage element, the electrical characterization and the numerical simulation of the processes of the writing and reading steps.
  • Electronic devices based on organic semiconductor materials:
    Organic electronics is a strong candidate for the development of large-area electronics on virtually every substrate, enabling ubiquitous integration of advanced optoelectronics functionalities. Turning a candidate into a real player requires a complexity quantum leap, from the realization of single unpatterned devices to the development of multiple, interconnected, interoperating devices developed on the same substrate and integrating the different functionalities. The complexity lies in two facts: i) different functions need, generally speaking, different materials to be deposited on the same substrate; ii) unlike inorganic counterpart, subtractive lithographic patterning can be hardly applied. Potentially appealing and large-area compliant technologies are especially those belonging to printing arts, such as flexography, gravure, inkjet, spray, etc. Research efforts are therefore devoted by our group to adapt these technologies to print functional materials and to suitably formulate organic semiconductors into printable inks.

The laboratory is responsible for the design, construction, characterization and modeling of organic devices, with particular emphasis on photodetectors and transistors, and for their integration in innovative optoelectronic systems. Concerning transistors, the laboratory has developed a solid expertise in the study of transport phenomena and charge injection, where the dependence of the mobility on charge carrier density, on electric field and its correlation with polymer molecular weight has been addressed. On the front of photodetectors, the laboratory investigated the physics of the processes of photogeneration and collection of charge and the development of architectures of devices in order to maximize the quantum efficiency and minimize the contributions of the dark currents. In addition to the detection of visible light and near-infrared, attention is paid to the indirect detection of X-ray photons for applications in the field of non-invasive diagnostics. The activities of transistors and photodetectors finally converge in the development of digital image sensors made by using innovative deposition techniques such as spray-coating and inkjet printing.
  • Equipment

  • Fig. 1. Organic thin film transistor mounted in a high vacuum chamber
    Fig. 2. Gold microelectrodes for electrical measurements of organic materials
    Copyright © Ing. Giorgio Uccellini 2009
    Fig. 3. Numerical simulation of the tunneling current density from the channel to the nitride traps in a SONOS memory
    S.M. Amoroso et al., in IEDM Tech. Dig., 540, 2010

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    The activity is conducted in laboratories located to Building 24 of the electronics section of the DEIB, in C. Golgi 40.