Frekventno ovisan dielektrični odziv spoja feroelektrik-dielektrik s negativnim električnim kapacitetom

master's thesis

• Title (english): Frequency dependent dielectric response of ferroelectric-dielectric junction with negative electric capacitance
• Author: Matija Piskač
• Mentor: Danko Radić (mentor)
• Committee member: Danko Radić (predsjednik povjerenstva)
• Committee member: Damir Pajić (član povjerenstva)
• Committee member: Željko Skoko (član povjerenstva)
• Committee member: Krešimir Kumerički (član povjerenstva)
• Committee member: Emil Tafra (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2020-06-19, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Svijet postaje sve više digitaliziran te se javlja sve veća potreba za pohranom podataka, čime raste i potrošnja električne energije. Povećana potrošnja očituje se u problemu generiranja topline u integriranim krugovima. Navedeni problem ima pozadinu u fizici tranzistora, gdje se zbog Boltzmanove raspodjele napajanje tranzistora ne može spustiti ispod 1V. Jedno moguće rješenje je negativni električni kapacitet koji pokazuju feroelektrični materijali. Pojava se može opisati u okviru Landauove teorije faznih prijelaza koja pokazuje da je uobičajeno rješenje s negativnim diferencijalnim kapacitetom nestabilno. Stavljanje sloja feroelektričnog materijala na dielektrik ispod vrata tranzistora, zbog rubnih uvjeta, stabilizira rješenje s negativnim kapacitetom te daje kumulativni efekt smanjenja recipročne strmine ispod napona praga, koja iznosi oko 60mV po dekadi u konvencionalnom tranzistoru. U ovom radu, proučit ćemo fiziku feroelektrika te opisati feroelektričnost u okviru Landauove teorije faznih prijelaza na primjeru klasičnog feroelektrika BaTiO_3. Potom ćemo na temelju Tsividisovog modela tranzistora i Maxwellovih jednadžbi odrediti uvjet stabilizacije te uz pomoć Landau-Khalatnikove jednadžbe riješiti dobiven sustav. Odredit ćemo dielektrični odziv spoja feroelektrik-dielektrik u ovisnosti o frekvenciji u linearnom režimu analitički, odnosno u nelinearnom režimu numerički uz pomoć programskog jezika Mathematica.

Abstract (english)

The world is becoming increasingly digitalized and there is a growing need for data storage, thus increasing electricity consumption. Increased consumption is reflected in the problem of heat generation in integrated circuits. This problem has a background in transistor physics where, due to the Boltzmann distribution, transistor voltage cannot be reduced below 1V. One possible solution to this is negative electrical capacitance exhibited by ferroelectric materials. The phenomenon can be described in the framework of Landau’s theory of phase transitions, which shows that the usual solution with negative differential capacitance is unstable. Placing a layer of ferroelectric material on the dielectric below the transistor’s gate, due to boundary conditions, stabilizes the solution with negative capacitance. This gives the cumulative effect of reducing the reciprocal slope below the threshold voltage, which is about 60mV per decade in a conventional transistor. In this diploma paper, we will study the physics of ferroelectrics and describe ferroelectricity within Landau’s theory of phase transitions using the classical ferroelectric BaTiO3 as an example. Then, based on the Tsividis transistor model and the Maxwell equations, we will determine the stabilization condition and solve the obtained system using the Landau-Khalatnikov equation. We will determine the frequency-dependent dielectric response of a ferroelectric-dielectric junction in the linear regime analytically and in the non-linear regime numerically, using the programming language Mathematica.

• Keywords: feroelektrici; dielektrični odziv; negativni električni kapacitet; MOSFET; Tsividis; Landauova teorija; Landau-Khalatnikov
• Keywords (english): ferroelectrics; dielektric response; negative electric capacitance; MOSFET; Tsividis; Landau theory; Landau-Khalatnikov
• Language: croatian
• URN:NBN: urn:nbn:hr:217:663047
• Study programme: Title: Physics; specializations in: Education; Course: Education; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra edukacije fizike (magistar/magistra edukacije fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-09-02 15:57:03