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Title:Nanometer-scale temperature measurements of phase change memory and carbon nanomaterials
Author(s):Grosse, Kyle L.
Director of Research:King, William P.
Doctoral Committee Chair(s):King, William P.
Doctoral Committee Member(s):Pop, Eric; Nam, SungWoo; Aluru, Narayana R.
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Nanometer-scale thermometry
Phase Change Memory
Ge2Sb2Te5 (GST)
Scanning Joule Expansion Microscopy (SJEM)
Finite Element Analysis (FEA)
Heat Transfer
Abstract:This work investigates nanometer-scale thermometry and thermal transport in new electronic devices to mitigate future electronic energy consumption. Nanometer-scale thermal transport is integral to electronic energy consumption and limits current electronic performance. New electronic devices are required to improve future electronic performance and energy consumption, but heat generation is not well understood in these new technologies. Thermal transport deviates significantly at the nanometer-scale from macroscopic systems as low dimensional materials, grain structure, interfaces, and thermoelectric effects can dominate electronic performance. This work develops and implements an atomic force microscopy (AFM) based nanometer-scale thermometry technique, known as scanning Joule expansion microscopy (SJEM), to measure nanometer-scale heat generation in new graphene and phase change memory (PCM) devices, which have potential to improve performance and energy consumption of future electronics. Nanometer-scale thermometry of chemical vapor deposition (CVD) grown graphene measured the heat generation at graphene wrinkles and grain boundaries (GBs). Graphene is an atomically-thin, two dimensional (2D) carbon material with promising applications in new electronic devices. Comparing measurements and predictions of CVD graphene heating predicted the resistivity, voltage drop, and temperature rise across the one dimensional (1D) GB defects. This work measured the nanometer-scale temperature rise of thin film Ge2Sb2Te5 (GST) based PCM due to Joule, thermoelectric, interface, and grain structure effects. PCM has potential to reduce energy consumption and improve performance of future electronic memory. A new nanometer-scale thermometry technique is developed for independent and direct observation of Joule and thermoelectric effects at the nanometer-scale, and the technique is demonstrated by SJEM measurements of GST devices. Uniform heating and GST properties are observed for mixed amorphous and crystalline phase GST. However, heterogeneous heating and GST phase distribution are observed for mixed crystalline phases of GST. The properties of GST thin films are evaluated using macroscopic and SJEM measurements. The thermopower of GST thin films depends on the local grain structure and has potential to significantly decrease future PCM energy consumption. This dissertation presents nanometer-scale thermometry measurements of Joule and thermoelectric effects in new graphene and PCM devices due to defects, interfaces, and grain structure: important for developing future electronics and increasing knowledge of nanometer-scale thermal transport.
Issue Date:2014-09-16
Rights Information:Copyright 2014 Kyle L. Grosse
Date Available in IDEALS:2014-09-16
Date Deposited:2014-08

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