Goodwill Jonathan M, Ramer Georg, Li Dasheng, Hoskins Brian D, Pavlidis Georges, McClelland Jabez J, Centrone Andrea, Bain James A, Skowronski Marek
Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA, 15213, USA.
Nanoscale Device Characterization Division, Physical Measurements Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
Nat Commun. 2019 Apr 9;10(1):1628. doi: 10.1038/s41467-019-09679-9.
Threshold switching devices are of increasing importance for a number of applications including solid-state memories and neuromorphic circuits. Their non-linear characteristics are thought to be associated with a spontaneous (occurring without an apparent external stimulus) current flow constriction but the extent and the underlying mechanism are a subject of debate. Here we use Scanning Joule Expansion Microscopy to demonstrate that, in functional layers with thermally activated electrical conductivity, the current spontaneously and gradually constricts when a device is biased into the negative differential resistance region. We also show that the S-type negative differential resistance I-V characteristics are only a subset of possible solutions and it is possible to have multiple current density distributions corresponding to the same value of the device voltage. In materials with steep dependence of current on temperature the current constriction can occur in nanoscale devices, making this effect relevant for computing applications.
阈值开关器件在包括固态存储器和神经形态电路在内的许多应用中变得越来越重要。它们的非线性特性被认为与自发（在没有明显外部刺激的情况下发生）电流流动收缩有关，但程度和潜在机制仍存在争议。在这里，我们使用扫描焦耳膨胀显微镜来证明，在具有热激活电导率的功能层中，当器件偏置到负微分电阻区域时，电流会自发且逐渐收缩。我们还表明，S型负微分电阻I-V特性只是可能解的一个子集，并且对于器件电压的相同值可能有多个电流密度分布。在电流对温度有陡峭依赖性的材料中，电流收缩可能发生在纳米级器件中，这使得这种效应与计算应用相关。
