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Digital archive of theses discussed at the University of Pisa


Thesis etd-03072024-123025

Thesis type
Tesi di dottorato di ricerca
Thesis title
Modeling and quantum transport simulation of electronic devices based on 2D materials and thin-film conductive oxides
Academic discipline
Course of study
tutor Prof. Iannaccone, Giuseppe
  • 2D materials
  • flexible electronics
  • landauer model
  • multiscale method
  • NEGF formalism
  • perovskites
  • quantum transport simulations
  • semiconductor physics
  • shot noise
  • tight binding model
  • transition metal oxides
  • transparent conductive oxides
Graduation session start date
This thesis presents various contributions towards modeling and simulating quantum transport of electronic devices based on 2D materials and thin-film conductive oxides. This allowed a better understanding of the physics behind the various materials studied, as well as the potential that these materials have for the fabrication of devices that can be competitive for future technological development.
The first original contribution of this thesis consists in model and simulation of a thermionic thin-film transistor made with La-BaSnO3 as channel material. The semi-analytical and self-consistent model is entirely written in Python and consists of a reinterpretation of the Landauer and the top of the barrier model. The model itself is already a non-trivial result, because it is easily adaptable and modifiable for different types of devices and materials, allowing to study the performance of devices through a small number of free parameters. Regarding the particular case of the La-BaSnO3 TFT, device modeling analysis indicate that La-BaSnO3-based TFTs hold great promise for high-performance active display applications.
The next step of this project consists to add dynamic behavior in the model by using the Cadence design suite and Verilog-A as programming language. This will allow us in the future to study TFT in more complex circuits, such as amplifiers or oscillators, and potentially model a floating gate memory and a vector matrix multiplier.
The second original contribution consists in the development of a model for the shot noise in a thermionic thin-film transistor, and the investigation of the behavior of the so-called Fano factor, in relation to the possibility of observing either a reduction or an enhancement of the shot noise, depending on the geometrical, physical and bias characteristics of the device. This work is interesting not only from a simulative point of view, but also in the fact that we can have insight into the physical nature and behavior of the shot noise, and this can make a big difference in the design and performance of electronic devices and circuits.
The third original contribution can be divided into two parts. Firstly, we analysed with a multiscale model the experimental data of a p-type NbS2/MoS2 2D hetero-junction. We use two-band, two-orbital, first-nearest-neighbors tight-binding model for the Hamiltonian of the junction, and we perform NEGF transport simulations. We extract some useful physical quantities that allow us to gain insight on the quality of the junction.
Secondly, thanks to the study of this junction, we tried to simulate a p-type FET made with the same materials. In particular, having in this case no experimental results, we put ourselves in ideal conditions (i.e. without traps and with a good heterointerface), and look at the upper-limit performance of the device. The simulations were performed with an in-house code by means of a self-consistent Schrodinger-Poisson algorithm in the NEGF formalism, in which we also included electron-phonon interactions.