Research Activity

Since 1992 he is working on the following items:

a) Design, characterization and modelling of Electrostatic Discharge (ESD) protection structures for CMOS and SMART POWER integrated circuits; 
The development of ESD protection structures based on characterization, testing and modelling of suitable test structures has been carried out on several CMOS and SMART POWER (BCD – Bipolar, CMOS, DMOS) technologies (including SOI, Silicon On Insulator). The devices have been studied by means of electrical and electroluminescence measurements and with the support of 2D electro-thermal drift-diffusion simulations (DESSIS-ISE). Within this context a new methodology has been identified for the development of ESD protection structures based on a synergistic use of both measurements and simulations that allow a strong reduction of the development time.

b) Electrical characterization, modelling and reliability of microwave devices on III-V semiconductors such as GaAs and InP (MESFETs, HEMTs and PHEMTs); 
A systematic study of the characteristics and the reliability of GaAs- and InP-based field effect transistors (MESFETs, HEMTs and PHEMTs) and bipolar junction transistors (HBT) has been carried out. The following aspects have been investigated: (i) characterization of the on-state and off-state device breakdown and measure of the electrons/holes impact ionization coefficient; (ii) Increasing of the breakdown voltage in InP-based HEMTs by the adoption of a new channel structure: InGaAs/InP composite channel and narrow (below 10 nm thickness) quantized channel; (iii) Study of the degradation modes and mechanisms in devices submitted to accelerated life tests (high fields and hot electrons regime at high temperatures); (iv) study of the surface device optimization in InP-based HEMTs for reliability improvements.

c) Electrical characterization, modeling and reliability of electronic and opto-electronic devices grown on wide bandgap semiconductors (SiC and GaN)
. A detailed characterization study of optoelectronics (LEDs) and microwave (MESFETs, HEMTs) based on wide bandgap semiconductors (Silicon Carbide, SiC and Gallium Nitride, GaN) has been carried out. The instabilities presents in these devices have been largely characterized (current collapse, kink effects, current transient behaviours, persistent photoconductivity, …) and attributed deep traps present within the device active area (surface or bulk). These anomalies are due to non yet optimized crystal growth (material still presents large defects density) due to the immaturity status of the technological process. Finally, several stress tests were conducted with the aim of identify degradation modes and  mechanisms in GaN HEMTs for the identification of technological solutions for the development robust and reliable devices.

d) Electrical characterization, modelling and reliability of RF-MEMS switches for reconfigurable antenna switches
. An electro-mechanical and rf characterization activity, as well as a detailed investigation of degradation modes and mechanisms of micromachined rf-MEMS (Micro-Electro-Mechanical-Systems) have been carried with several goals. The main focus has been the (i) electro-mechanical analysis of switches behavior, in order to fully assess such devices from both the electrical and rf point of view, and from the mechanical one, being constituted by movable parts. To do that, a deep investigation of (ii) the best characterization procedures has been done, and ad-hoc measurement setups were developed. Failure and degradation mechanisms have been studied with the aim of (iii) find out accelerating factors in order to speed up aging tests, adopting also exotic procedures, like ESD and radiation stresses, as well as mechanical shocks. This activity is also useful in order to improve the knowledge of the behavior of such devices in harsh environments, like the spatial one. Furthermore, test structures and SPST and SPDT rf switches have been designed and electro-mechanically modeled by means of simplified simulations as well as finite-element-method (FEM) ones.

e) Development of organic electronics for low cost, low power, large area applications. The research efforts has been devoted to the investigation of the most important factors that limit the performance and the reliability of state-of-the-art organic semiconductor devices for electronics and optoelectronics applications (Organic Thin-Film Transistors, Organic Light-Emitting Diodes, Organic Solar Cells). Even though these devices have different structures, they present a set of common critical aspects that need to be investigated with the aim of improving performance, stability, and reliability. The research interests range over a wide variety of subjects: i) the characterization of the properties and stability of organic materials and devices. ii) the investigation of devices reliability dependence on stress parameters (e.g., voltage, current, or temperature) and the extrapolation of the device degradation laws. iii) the study of the impact of the structural parameters (e.g., layer composition and thickness, contact materials, …) on the reliability of the devices. iv) the determination of the factors that limit the reliability of organic devices.

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