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Ferroelectric Memory Based on Partial Polarization for Analog Weight Storage.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Ferroelectric Memory Based on Partial Polarization for Analog Weight Storage./
Author:	Pandey, Pratyush.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
Description:	249 p.
Notes:	Source: Dissertations Abstracts International, Volume: 83-01, Section: B.
Contained By:	Dissertations Abstracts International83-01B.
Subject:	Electrical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28418433
ISBN:	9798516957093

Ferroelectric Memory Based on Partial Polarization for Analog Weight Storage.
Pandey, Pratyush.

Ferroelectric Memory Based on Partial Polarization for Analog Weight Storage. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 249 p.

Source: Dissertations Abstracts International, Volume: 83-01, Section: B.

Thesis (Ph.D.)--University of Notre Dame, 2021.

This item must not be sold to any third party vendors.

The dynamics of reading and writing the partial polarization state in ferroelectric (FE) capacitors have been explored for use in nonvolatile analog memory for application in training neural networks. New pulse measurement protocols that minimize spurious interface charging effects have been developed to more precisely measure polarization, polarization reversal, and current-voltage characteristics. Analytic methods to interpret these measurements have also been developed.A strictly symmetric pulse protocol, where the integral of the measurement waveform over a measurement cycle is zero, was developed to measure dynamic effects in FE capacitors. In this way, the effects of biasing were balanced equally to minimize charging of the interfaces. Unsaturated polarization reversal was observed in TiN/HZO/TiN capacitors with asymmetric measurements; the unsaturation was substantially eliminated using the strictly symmetric protocol.Using the strictly symmetric measurement protocol, partial polarization in metal-FE-metal capacitors was shown to be stable up to 250 ms. A surprising dependence of partial polarization on the delay between reset and write pulses, and the reset conditions, was discovered, with the partial polarization changing by 50% of the FE remanent polarization. This delay-before-write dependence was qualitatively attributed to the dynamics of subcritical nuclei that exist up to 1 s in HZO, and whose size is estimated to be less than 4x4x4 HZO unit cells.A strictly symmetric pulsed protocol was designed for current-voltage-time (I-V-t) measurements on Pd/HZO/p+ Si capacitors. The I-V-t measurements showed the capacitor current direction to be opposite to the applied bias polarity for voltages lower in magnitude than certain characteristic zero crossing voltages. The current magnitudes increased when the applied bias magnitudes were decreased further. A quantitative analysis showed these observations to be consistent with the assumption that the HZO electric field controls the capacitor current direction, and that a flat band condition exists in HZO at the zero crossing voltages.A spectroscopic photoresponse measurement system was constructed, capable of measuring electrical responses to photons ranging in energy from 0.6 - 7 eV, to measure polarization dependent band offsets of metal-FE-semiconductor capacitors by internal photoemission (IPE). The bandgap of HZO was extracted as 6.2 +/- 0.2 eV from Pd/HZO IPE transitions.

ISBN: 9798516957093Subjects--Topical Terms:

649834
Electrical engineering.
Subjects--Index Terms:

Ferroelectric analog memory

Ferroelectric Memory Based on Partial Polarization for Analog Weight Storage.
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100 1 $a Pandey, Pratyush. $3 3319326
245 1 0 $a Ferroelectric Memory Based on Partial Polarization for Analog Weight Storage.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 2021
300 $a 249 p.
500 $a Source: Dissertations Abstracts International, Volume: 83-01, Section: B.
500 $a Advisor: Seabaugh, Alan C.
502 $a Thesis (Ph.D.)--University of Notre Dame, 2021.
506 $a This item must not be sold to any third party vendors.
520 $a The dynamics of reading and writing the partial polarization state in ferroelectric (FE) capacitors have been explored for use in nonvolatile analog memory for application in training neural networks. New pulse measurement protocols that minimize spurious interface charging effects have been developed to more precisely measure polarization, polarization reversal, and current-voltage characteristics. Analytic methods to interpret these measurements have also been developed.A strictly symmetric pulse protocol, where the integral of the measurement waveform over a measurement cycle is zero, was developed to measure dynamic effects in FE capacitors. In this way, the effects of biasing were balanced equally to minimize charging of the interfaces. Unsaturated polarization reversal was observed in TiN/HZO/TiN capacitors with asymmetric measurements; the unsaturation was substantially eliminated using the strictly symmetric protocol.Using the strictly symmetric measurement protocol, partial polarization in metal-FE-metal capacitors was shown to be stable up to 250 ms. A surprising dependence of partial polarization on the delay between reset and write pulses, and the reset conditions, was discovered, with the partial polarization changing by 50% of the FE remanent polarization. This delay-before-write dependence was qualitatively attributed to the dynamics of subcritical nuclei that exist up to 1 s in HZO, and whose size is estimated to be less than 4x4x4 HZO unit cells.A strictly symmetric pulsed protocol was designed for current-voltage-time (I-V-t) measurements on Pd/HZO/p+ Si capacitors. The I-V-t measurements showed the capacitor current direction to be opposite to the applied bias polarity for voltages lower in magnitude than certain characteristic zero crossing voltages. The current magnitudes increased when the applied bias magnitudes were decreased further. A quantitative analysis showed these observations to be consistent with the assumption that the HZO electric field controls the capacitor current direction, and that a flat band condition exists in HZO at the zero crossing voltages.A spectroscopic photoresponse measurement system was constructed, capable of measuring electrical responses to photons ranging in energy from 0.6 - 7 eV, to measure polarization dependent band offsets of metal-FE-semiconductor capacitors by internal photoemission (IPE). The bandgap of HZO was extracted as 6.2 +/- 0.2 eV from Pd/HZO IPE transitions.
590 $a School code: 0165.
650 4 $a Electrical engineering. $3 649834
650 4 $a Monte Carlo simulation. $3 3564916
650 4 $a Random access memory. $3 623617
650 4 $a CMOS. $3 3681646
650 4 $a Arrays. $3 3681398
650 4 $a Transistors. $3 713271
650 4 $a Single crystals. $3 3681642
650 4 $a Optics. $3 517925
650 4 $a Ferroelectrics. $3 3681651
650 4 $a Electric fields. $3 880423
650 4 $a Calibration. $3 2068745
653 $a Ferroelectric analog memory
653 $a Ferroelectric hafnia
653 $a Ferroelectric partial polarization
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690 $a 0752
710 2 $a University of Notre Dame. $b Electrical Engineering. $3 2097603
773 0 $t Dissertations Abstracts International $g 83-01B.
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791 $a Ph.D.
792 $a 2021
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28418433