Ultralow-power switching via defect engineering in germanium telluride phase-change memory devices

Abstract

Crystal–amorphous transformation achieved via the melt-quench pathway in phase-change memory involves fundamentally inefficient energy conversion events; and this translates to large switching current densities, responsible for chemical segregation and device degradation. Alternatively, introducing defects in the crystalline phase can engineer carrier localization effects enhancing carrier–lattice coupling; and this can efficiently extract work required to introduce bond distortions necessary for amorphization from input electrical energy. Here, by pre-inducing extended defects and thus carrier localization effects in crystalline GeTe via high-energy ion irradiation, we show tremendous improvement in amorphization current densities (0.13–0.6 MA cm−2) compared with the melt-quench strategy (∼50 MA cm−2). We show scaling behaviour and good reversibility on these devices, and explore several intermediate resistance states that are accessible during both amorphization and recrystallization pathways. Existence of multiple resistance states, along with ultralow-power switching and scaling capabilities, makes this approach promising in context of low-power memory and neuromorphic computation.

Unconventional Inorganic‐Based Memristive Devices for Advanced Intelligent Systems

“…The operation properties of the PCM have been improved through the introduction of new phase switching materials, impurity doping, defect control, and strain engineering . Kao et al reported fast switching and long retention properties of the PCM device based on Ga 2 Te 3 Sb 5 .…”

Inverting polar domains via electrical pulsing in metallic germanium telluride

“…In conjunction with in situ transmission electron microscope (TEM) characterization of the GeTe devices27282930, we studied the interaction of these domains and domain boundaries with extended defects such as anti-phase boundaries (APBs) and associated partial dislocations created by heat shocks from current pulses. Furthermore, we show that neither static fields nor steady currents can couple to the domain polarizations, emphasizing that the only possible external electrical stimulus that can do so are the electrical pulses.…”

Nanotwin Detection and Domain Polarity Determination via Optical Second Harmonic Generation Polarimetry

“…Since the domain size is very large (>100 µm) and each domain exhibits very weak SHG signal in this case, an individual twin boundary that only has one single polarity can be found easily via SHG and then characterized in detail. For an intermediate-sized domain (>10 µm), the nature of the boundaries can be determined by 4 detecting each domain via 2D or 3D SHG microscopy if it is non-centrosymmetric, e.g. polycrystalline monolayer MoS 2 28 .…”

“…in twinned CdTe nanowires). The SHG technique can be extended to any noncentrosymmetric single-crystalline material not only at the nanoscale but also for bulk materials which are impossible to characterize via TEM and to study the nature of defects in devices inoperando[2][3][4] . The versatility and flexibility of this technique can improve our understanding of precise structure-property relationships in materials.…”