Microscopic Complexity in Phase‐Change Materials and its Role for Applications

Abstract

Phase‐change materials (PCMs) are widely used for data storage and in other functional devices. Despite their seemingly simple compositions, these materials exhibit intriguing microscopic complexity and a portfolio of interesting properties. In this Feature Article, it is shown that structural and electronic peculiarities on the atomic scale are key determinants for the technological success of PCMs. Particular emphasis is put on the interplay of different experimental and theoretical methods, on the bonding nature of crystalline and amorphous PCMs, and on the role of surfaces and nanostructures. Then, unconventional transport properties of the crystalline phases are highlighted, both with regard to electrical and heat conduction. Finally, perspectives and future directions are drawn: for finding new PCMs based on microscopic understanding, and also for new applications of these materials in emerging fields.

Exploring the subsurface atomic structure of the epitaxially grown phase-change material Ge2Sb2Te5

“…This should eventually expose structure-property relationships to be employed for the optimization of materials and their combination into novel types of composites [10]. The ongoing miniaturization of cells, though, increases the influence of surfaces and interfaces, which might be different from their bulk counterparts in terms of the atomic arrangement [11,12]. Hence the atomic structure and the resulting properties in these distinct areas must be explored in detail, too.…”

“…Here, we explore STM and STS on the prototype phasechange material GST-225 [1,11], grown epitaxially by molecular beam epitaxy (MBE) [21][22][23][24][25]. This provides the first STM study on single crystalline phase-change materials.…”

Особенности распределения электронной плотности в теллуриде сурьмы Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-

“…PCM в настоящее время используются для изготовления раз-личных видов оптической перезаписываемой памяти -компакт-дисков (CD), цифровых универсальных дисков (DVD), дисков на основе Blu-Ray технологии [3]. Высоко также оцениваются потенциальные возможности созда-ния на основе PCM энергонезависимой электронной памяти [4,5].…”

“…Признано, что выяснение природы химической связи в PCM является ключевым моментом для понимания их свойств [5]. В ряде работ для описания кристаллических и аморфных полупроводников [10] и PCM [5,11] привле-калась идея о резонансной связи (resonance bonding), высказанная Полингом в его книге [12]. Основанная на квантовомеханических расчетах электронной струк-туры простейших двухатомных молекул, эта идея была, несомненно, полезна для качественного анализа свойств существенно более сложных многоатомных молекул.…”

Interband characterization and electronic transport control of nanoscaledGeTe/Sb2Te3superlattices

“…Phase-change materials (PCMs) constitute a class of semiconductors characterized by two allotrope phases, a crystalline and an amorphous one, having distinct physical properties [1,2]. Such materials, discovered in the late 60s [3], are already used in rewritable optical discs, such as DVDs and Blu-ray discs.…”