The group of electrical characterization of materials and electronic devices has developed a set of standard techniques based on the analysis of conduction mechanisms and electrical parameters (capacity, conductance, current, etc.), which allow for a detailed study. of a wide variety of phenomena related to the existence of defects and impurities in semiconductors, with effects linked to the parameters used in the processes of microelectronic technology, etc. Modifications to standard techniques have also been made in order to apply them to particular structures, which has led to the development and application of new variants and original techniques that are more precise or more appropriate in certain circumstances. Thus, and by way of example, we have developed the following techniques:

In recent years, the study of high permittivity dielectric materials has become one of the objectives of our research group. In a first stage, we carried out this study in two aspects: on the one hand, in collaboration with researchers from the Complutense University of Madrid, we focused on characterizing the electrical properties of silicon nitride films deposited by ECR-CVD; On the other hand, in collaboration with researchers from the Bell Laboratories of Murray Hill (NJ, USA) we studied a very promising material in this field: tantalum oxide. This work was started during the stay of two members of the group (Helena Castán and Salvador Dueñas) at the Bell Laboratories of Lucent Technologies.

Currently, our interest is focused on the study of high permittivity dielectrics that can replace silicon oxide in future generations of integrated circuits. These dielectrics are mainly manufactured using two growth techniques. The first of these manufacturing methods is the promising Atomic Layer Deposition (ALD) technique. Until now, this line has been developed and maintained thanks to the collaboration of our group with European research laboratories located in Finland (inventor group of the technique), Estonia and Sweden. Currently we are also collaborating with the National Center for Microelectronics to implant this technique in its center in Barcelona. The second of the techniques is called "High Pressure Reactive Sputtering (HPS)" and consists of a sputtering technique in which the pressure of the chamber is maintained at values ​​much higher than usual in order to minimize the damage caused on substrates. In order to carry out a fine characterization of these materials, we have developed two experimental methods that avoid certain limitations presented by commonly used techniques. The denomination, in English, that we have chosen for these techniques are: Conductance Transient Technique (G-t), and Flat-Band Transient Technique (VFB-t).

Metal-insulating-semiconductor structures (MIS present some problems related to the quality of the interface between semiconductor and insulator. Therefore, these structures must be carefully characterized. Standard electrical measurements for these structures are usually carried out using CV and DLTS techniques. In recent years we have shown that transient conductance (Gt) measurements provide quantitative information on DIGS (disorder induced gap states).

The flat band transients technique allows to quantitatively analyze the instabilities observed in MIS devices and MOSFET transistors caused by the existence of so-called slow traps in high permittivity dielectrics. The loading and unloading processes of these traps degrade the properties of the devices as they lead to drifts in the threshold voltage of the transistors and reduce the mobility and half-life of the carriers in the channel. We have recently developed this technique to demonstrate the existence of flat band voltage transients in ultra-thin high-permittivity dielectrics.

The cast of high permittivity dielectrics that we have studied so far with the above manufacturing and characterization techniques includes an already wide variety: Silicon Nitride, Tantalum Oxides, Titanium, Hafnium, Zirconium, Aluminum and Gadolinium, Hafnium and Zirconium Silicates , multilayers and combinations of the above, among others.

        Currently our group is starting new activities oriented towards more applied fields. Along these lines, we try to collaborate with companies in the local industrial sector with the aim of improving their applications and products. Specifically, we have started a collaboration in the area of ​​solar cells and photovoltaic devices with the company PEVAFERSA. Another line of research consists of a feasibility study of MEMS-type microelectronic devices (accelerometers, surface wave sensors, ...) for applications in the field of Electroacoustics. One company that has expressed its interest in this subject is the AUDIOTEC company. The two companies mentioned have their headquarters in the Boecillo Technology Park.