Alessandro Paghi

Alessandro Paghi
Italian National Research Council | CNR · Institute of Nanoscience NANO

Electronic Engineer
Micro- and nano- structured materials, devices, and systems for DC-to-GHz electronics and UV-VIS-NIR photonics.

About

16
Publications
1,744
Reads
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102
Citations
Citations since 2017
16 Research Items
102 Citations
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Introduction
I received my M.Sc. and Ph.D. cum laude in Electronic and Information Engineering from the University of Pisa in 2018 and 2022, respectively. Currently, I am post-doctoral researcher at the Nanoscience Department of the Italian National Research Council focusing on the development of micro- and nano- structured materials, devices, and systems for unconventional DC-to-GHz electronics and UV-VIS-NIR photonics.
Additional affiliations
November 2018 - November 2021
Università di Pisa
Position
  • PhD Student
Education
October 2016 - September 2018
Università di Pisa
Field of study
  • Electronic Engineering
October 2013 - July 2016
Università degli Studi di Siena
Field of study
  • Information Engineering

Publications

Publications (16)
Article
Rapid progress in the synthesis and fundamental understanding of 1D and 2D materials have solicited the incorporation of these nanomaterials into sensor architectures, especially field effect transistors (FETs), for the monitoring of gas and vapor in environmental, food quality, and healthcare applications. Yet, several challenges have remained una...
Article
Full-text available
Here, the authors report on the manufacturing and in vivo assessment of a bioresorbable nanostructured pH sensor. The sensor consists of a micrometer‐thick porous silica membrane conformably coated layer‐by‐layer with a nanometer‐thick multilayer stack of two polyelectrolytes labeled with a pH‐insensitive fluorophore. The sensor fluorescence change...
Article
Nanoparticle-polymer composites hold promise in enabling material functionalities that are difficult to achieve otherwise, yet are hampered to date by the scarce control and tunability of the nanoparticle collective properties on the polymer surface, especially for polymer foams featuring a complex three-dimensional pore network. Here we report on...
Article
Full-text available
Salivary analysis is gaining increasing interest as a novel and promising field of research for the diagnosis of neurodegenerative and demyelinating diseases related to aging. The collection of saliva offers several advantages, being noninvasive, stress-free, and repeatable. Moreover, the detection of biomarkers directly in saliva could allow an ea...
Article
Full-text available
Here the 4D printing of a magnifying polydimethylsiloxane (PDMS) lens encoded with a tunable plasmonic rejection filter is reported. The lens is formed by moldless printing of PDMS pre-polymer on a nanostructured porous silicon (PSi) templating layer. A nanometer-thick plasmonic filter is integrated on the lens surface by in situ synthesis of Ag an...
Article
Full-text available
Here, the formation of carbon nanotube (CNT)‐based nanohybrids in aqueous solution is reported, where DNA‐wrapped CNTs (DNA‐CNTs) act as templates for the growth of PbS and CdS nanocrystals, toward the formation of PbS‐DNA‐CNT and CdS‐DNA‐CNT heterostructures. Solution‐processed multiplexed photoresponsive devices are fabricated from these nanohybr...
Article
Full-text available
Here, a fluoride‐assisted route for the controlled in‐situ synthesis of metal nanoparticles (NPs) (i.e., AgNPs, AuNPs) on polydimethylsiloxane (PDMS) is reported. The size and coverage of the NPs on the PDMS surface are modulated with time and over space during the synthetic process, leveraging the improved yield (10×) and faster kinetics (100×) of...
Article
Over the past two decades, different nanomaterials have been proposed for the design of novel silicon-based electronic devices or to push the performance of existing ones, leveraging the unique properties of charge carriers traveling in meso-to-nano scale structures. Porous silicon (PSi) is the nano- (n-PSi) to micro- (m-Psi) structured form of sil...
Article
The increasing request of on-chip energy storage devices is driven by the augmented connectivity between people and things for IoT, portable, and wearable electronic applications. These systems require high performance components with low power consumption, compact size, and high energy storage capability. Supercapacitors (SCs) achieve capacitance...
Article
Nanomaterials hold the promise of revolutionizing electronics and, in turn, its applications, thanks to the unique properties of charge carriers traveling in structures with length scale down to a few nanometers. Here, the tremendous reduction of mobility and lifetime of charge carriers when traveling in randomly arranged nanostructured silicon cry...
Article
The currently growing request for a continuous connectivity between people and things has increased exponentially the demand for portable and/or wearable electronics. Thus, high performance components with more compact size, lower power consumption, and increased energy storage capability are needed. Although electronic active components have downs...
Article
Capacitors are the most critical passive components of future in-package and on-chip electronic systems with augmented energy-storage capabilities for consumer and wearable applications. Although an impressive increase of both capacitance and energy densities has been achieved over the last years for supercapacitors (SCs), electronic applications o...
Article
Gold nanoparticle layers (AuNPLs) enable the coupling of morphological, optical and electrical properties of AuNPs in liquid dispersion with tailored and specific surface topography, making them exploitable in many bio-applications (e.g. biosensing, drug delivery, photothermal therapy). Herein, we report the formation of AuNPLs on porous silicon (P...
Article
Herein, we report low concentration ethanol vapor detection with nanostructured porous silicon (PSi) interferometers using Interferogram Average over Wavelength Reflectance Spectroscopy (IAWRS), a novel interferometric technique recently developed for ultrasensitive (bio)sensing applications in liquid using miniaturized integrated interferometers....

Questions

Question (1)
Question
Hi everyone,
I am working with SU8 2075 and I found some issues with the edge reflow.
This is the experimental protocol:
- 3'' Si wafers were used as substrates. Wafers are cleaned using ACE (10 min), IPA (10 min) Piranha (H2SO4:H2O2 3:1) (30 min), dehydration (30 min@ 250 °C).
- A quantity of SU-8 2075 was casted on the middle of the wafer. I started trying 3.6 g (that is about 1.2 g x inch, as suggeste by the manual 1 mL x inch). I tryed also to reduce the quantity to 2.5 g or 2 g of resist. I tryed to cast the resist on the middle, or span the resist over the substrate using a syringe needle or tilting the wafer.
- Wafer was moved in the spin coater and different rotation speeds were tested for the coating. First step: 500 RPM @ 100 RPM/s for 15s
Second step: desidered RPM @ 300 RPM/s for 30 s
I tryied 1000, 1500, 2000, 2500, 3000 RPM for the second step.
- The bottom side of the wafer was cleaned from photoresist excess
- Wafer was positioned over a bubble-levelled hotplate. I tryed ramp the temperature from RT to 65 °C, wait the desidered time, the ramp to 65 °C to 95 °C, wait the disedered time, with ramp rate of 5°C/min. I also tryed to put the wafer directly on hot hotplate at 65 or 95 °C.
I found the following issues:
- If the resist was casted on the middle without span it over the surface, a sort of signature of the position of the resist after the drop casting step remain after the spin coating. Probably it is related to a sort of drying of the dropped resist surface I think...
- After the spin coating step, on the edge of the wafer there is an amount of resist: the edge beads. This edge is about 2-3 mm extension on the wafer. But, when the wafer was placed over the hotplate, the edge became larger and larger and increase with the temperature and time. This is the so-called reflow process.
When I use low spin coating speed (1000 RPM), the reflow allows the edge to reach the wafer center and planarize the wafer thickness all over the substrate.
On the other hand, when I use high spin coating speed (3000 RPM), the reflow is limited and the resist thickness is due to the photoresist spin and not from the edge reflow.
At middle spin coating speed (1500 - 2500 RPM), the reflow does not allow the edge to reach the wafer center and planarize the wafer thickness all over the substrate. As consequence, I obtain large edge (about 2 cm) and small working area on the center.
I am not sure, but I would to understand if the reflow is something wanted or unwanted using SU-8. If yes, how I can have it anytimes, also with middle spin coating speed. If not, how I can avoid it?

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