Návrh tranzistoru řízeného polem využívajícího statickou zápornou kapacitu feroelektrického nanodoménového zárodku
Loading...
Date
2023-06-21
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Diplomová práce se věnuje hypotéze, která je v současné době intenzivně zkoumána v odborné literatuře a která konstatuje, že pomocí feroelektrických materiálů je možné snížit rozkmit napětí na hradle unipolárního tranzistoru. Rozkmit napětí je dán tzv. Boltzmannovou tyranií, která stanoví, že pro desetinásobné zvětšení proudu tekoucího unipolárním tranzistorem je nutné zvýšit napětí na hradle o 60 mV. Toto omezení v současné době brání dalšímu snižování spotřeby unipolárních tranzistorů. Cílem této práce je analyzovat vliv nanodoménového zárodku ve feroelektrickém kondenzátoru na napětí na kanálu v tranzistoru řízeným elektrickým polem. V diplomové práci byly vytvořeny analytické a numerické modely transistoru s feroelektrickou vrstvou. V rámci analytického modelu byl odvozen analytický vztah pro popis zesílení na kanále pomocí dvou sériově zapojených kondenzátorů. Dále byla provedena základní analýza stability záporné permitivity ve feroelektriku, které je součástí dvojvrstvy feroelektrikum-dielektrikum. V rámci numerického modelu byly provedeny simulace tranzistoru s hypotetickou dielektrickou vrstvou se zápornou permitivitou. Na numerickém modelu je ukázáno, že přítomnost volných nosičů nábojů ovlivňuje elektrická pole v MOSFETu a tedy, že jednoduchý analytický model sériového zapojení dvou kondenzátorů, který se často ve vědecké literatuře používá, je nepoužitelný pro přesný návrh tranzistoru. Dále byly provedeny numerické simulace modelu tranzistoru s feroelektrickou vrstvou, která obsahuje nanodoménový zárodek. Na těchto simulacích se podařilo prokázat přítomnost negativní diferenciální permitivity ve feroelektriku.
This thesis explores the hypothesis, which is currently intensively investigated in the scientific literature, that by using ferroelectric materials, it is possible to reduce the subtreshold swing on the gate of a unipolar transistor. The subtreshold swing is given by the so-called Boltzmann tyranny, which states that to increase the current flowing through a unipolar transistor tenfold, it is necessary to increase the gate voltage by 60 mV. This constraint currently prevents further reduction of the power consumption of unipolar transistors. The aim of this work is to analyze the effect of a nanodomain nucleus in a ferroelectric capacitor on the channel voltage in a field effect transistor. In this thesis, analytical and numerical models of a transistor with a ferroelectric layer have been developed. Within the analytical model, an analytical relation was derived to describe the gain on the channel using two capacitors connected in series. In addition, a basic analysis of the stability of the negative permittivity in the ferroelectric layer, which is part of the ferroelectric-dielectric double layer, was performed. Numerical model simulations of a transistor with a hypothetical dielectric layer with negative permittivity were performed. It is shown in the numerical model that the presence of free charge carriers affects the electric fields in the MOSFET and, therefore, that the simple analytical model of a series connection of two capacitors, which is often used in the scientific literature, is inapplicable for accurate transistor design. Furthermore, numerical simulations of a transistor model with a ferroelectric layer containing a nanodomain nucleus were performed. These simulations were able to demonstrate the presence of negative differential permittivity in the ferroelectric layer.
This thesis explores the hypothesis, which is currently intensively investigated in the scientific literature, that by using ferroelectric materials, it is possible to reduce the subtreshold swing on the gate of a unipolar transistor. The subtreshold swing is given by the so-called Boltzmann tyranny, which states that to increase the current flowing through a unipolar transistor tenfold, it is necessary to increase the gate voltage by 60 mV. This constraint currently prevents further reduction of the power consumption of unipolar transistors. The aim of this work is to analyze the effect of a nanodomain nucleus in a ferroelectric capacitor on the channel voltage in a field effect transistor. In this thesis, analytical and numerical models of a transistor with a ferroelectric layer have been developed. Within the analytical model, an analytical relation was derived to describe the gain on the channel using two capacitors connected in series. In addition, a basic analysis of the stability of the negative permittivity in the ferroelectric layer, which is part of the ferroelectric-dielectric double layer, was performed. Numerical model simulations of a transistor with a hypothetical dielectric layer with negative permittivity were performed. It is shown in the numerical model that the presence of free charge carriers affects the electric fields in the MOSFET and, therefore, that the simple analytical model of a series connection of two capacitors, which is often used in the scientific literature, is inapplicable for accurate transistor design. Furthermore, numerical simulations of a transistor model with a ferroelectric layer containing a nanodomain nucleus were performed. These simulations were able to demonstrate the presence of negative differential permittivity in the ferroelectric layer.
Description
Subject(s)
záporná kapacita, feroelektřina, MOSFET