217 research outputs found
Defect Level Switching for Highly-Nonlinear and Hysteretic Electronic Devices
Nonlinear and hysteretic electrical devices are needed for applications from
circuit protection to next-generation computing. Widely-studied devices for
resistive switching are based on mass transport, such as the drift of ions in
an electric field, and on collective phenomena, such as insulator-metal
transitions. We ask whether the large photoconductive response known in many
semiconductors can be stimulated in the dark and harnessed to design electrical
devices. We design and test devices based on photoconductive CdS, and our
results are consistent with the hypothesis that resistive switching arises from
point defects that switch between deep- and shallow-donor configurations:
defect level switching (DLS). This new electronic device design principle -
photoconductivity without photons - leverages decades of research on
photoconductivity and defect spectroscopy. It is easily generalized and will
enable the rational design of new nonlinear, hysteretic devices for future
electronics.Comment: Text and supplemental merged into one fil
Atomic Structure of Domain and Interphase Boundaries in Ferroelectric HfOâ‚‚
Though ferroelectric HfOâ‚‚ thin films are now well characterized, little is currently known about their grain substructure. In particular, the formation of domain and phase boundaries requires investigation to better understand phase stabilization, switching, and phase interconversion. Here, scanning transmission electron microscopy is applied to investigate the atomic structure of boundaries in these materials. It is found that orthorhombic/orthorhombic domain walls and coherent orthorhombic/monoclinic interphase boundaries form throughout individual grains. The results inform how interphase boundaries can impose strain conditions that may be key to phase stabilization. Moreover, the atomic structure near interphase boundary walls suggests potential for their mobility under bias, which has been speculated to occur in perovskite morphotropic phase boundary systems by mechanisms similar to domain boundary motion
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