Electronics > Microelectronics and Emerging Technologies > Electron devices

Lacaita Andrea Leonardo
Longoni Antonio Francesco
Sampietro Marco

http://risorse.dei.polimi.it/MicroLab/
http://home.dei.polimi.it/sampietr/index.html

Focus

The research is focused on the design, the experimental characterization and the numerical modeling of innovative electronic devices and covers the following topics:

Flash memory reliability:
The research is devoted to the investigation of the new physical phenomena constraining the reliability of NOR and NAND Flash memories as these enter the nanometer scale, suggesting experimental methodologies and providing physics-based modeling to tackle the new physical issues and preserve device functionality. RTN fluctuations, few electron phenomena and cycling-induced instabilities are just examples of the investigated physical effects.

Innovative technologies for post-Flash scenario:
The research addresses novel memory devices, such as phase-change memory (PCM), resistive switching memory (RRAM) and conductive-bridge memory (CBRAM). Experiments at variable temperature (20 – 600K) and time resolution (5ns – few months) are carried out to assess switching and reliability characteristics. Based on the experimental results, physical models for transport and switching phenomena are developed, allowing to gain a perspective into the scaling potential of these new technologies.

Organic semiconductor devices:
The research is focused on i) the investigation of carrier transport in amorphous layers through the realization and modeling of organic field effect transistors, focusing on the issue of contact resistances and ii) on the study of the interaction of light with small molecules blends through the development and characterization of organic photodetectors aimed at near infrared radiation harvesting and at indirect x-ray detection.

Access to the electronic properties of devices at the nanoscale through novel instrumentation:
Main focus is the development of instrumentation for noise analysis of nanodevices, aiming at studying single spin resonant phenomena through single charge trapping/detrapping in MOSFETs under strong magnetic fields and at sub-kelvin temperatures. The electrical properties of biological materials are also investigated, with emphasis on the electrical response of mammal olfactory receptors upon interaction with specific odorants, to explore high sensitive and selective bio-sensors.




Fig. 1. Microelectrodes for electrical measurements in liquid of biological material, connected to the integrated circuit for signal processing
Copyright © Ing. Giorgio Uccellini 2009
Fig. 2. Numerical simulation of the thermal cross-talk between two neighboring PCM cells
A. Redaelli et al., J. Appl. Phys., 103, 111101, 2008


Slideshow peer review 2007

Most relevant research achievements


Flash memory reliability
The basic-physics behind RTN, few-electron phenomena, threshold-voltage instabilities after cycling, has been successfully explained by means of experimental and modeling activities, deriving design guidelines for next generation Flash technology nodes.

Innovative technologies for post-Flash scenario
The group has contributed solving most of the open issues about the switching and reliability of novel resistive memories, including set/reset mechanisms in PCM and RRAM, the resistance change in PCM due to structural relaxation and crystallization and the scaling laws for reset current and cross talk in PCM, thus helping the memory industry to assess the huge potential of these novel technologies.

Organic semiconductor devices
The research contributed to the analysis of contact resistances in polymer field-effect transistors, leading to an increased comprehension of the fundamental issue of charge injection into organic semiconductors.
The adoption of organic molecules belonging to the squaraine family allowed the fabrication of efficient (EQE>15%) and air stable detectors spectrally suited to near infrared and indirect X-ray detection.

Access to the electronic properties of devices at the nanoscale through novel instrumentation
Innovative transimpedance amplifiers have been designed to measure currents produced by nanodevices with extremely high sensitivity (15fA in 1ms) and on a large bandwidth (up to 1MHz) thus enabling the investigation of the physical properties of dielectric materials (eg. single-layer biomembrane) by capacitance maps with attoFarad resolution in conjunction with an AFM.