Fang, Nicholas | Search NASA

DOE OSTI2023

Multi-beam resin curing system and method for whole-volume additive manufacturing

A multi-beam volumetric resin curing system and method for whole-volume additive manufacturing of an object includes a bath containing a photosensitive resin, a light source for producing a light beam, and a spatial light modulator which produces a phase- or intensity-modulated light beam by impressing a phase profile or intensity profile of an image onto a light beam received from the light source. The system and method also include projection optics which then produces multiple sub-image beams from the modulated light beam which are projected to intersect each other in the photosensitive resin to cure select volumetric regions of the resin in a whole-volume three-dimensional pattern representing the object.

Shusteff, Maxim↗

DOE OSTI2022

Electronegative metal dopants improve switching variability in Al 2 ⁢O 3 resistive switching devices

Resistive random-access memories are promising for nonvolatile memory and brain-inspired computing applications. High variability and low yield of these devices are key drawbacks hindering reliable training of physical neural networks. In this paper, we show that doping an oxide electrolyte, Al 2 ⁢O 3 , with electronegative metals makes resistive switching significantly more reproducible, surpassing the reproducibility requirements for obtaining reliable hardware neuromorphic circuits. Based on density functional theory calculations, the underlying mechanism is hypothesized to be the ease of creating oxygen vacancies in the vicinity of electronegative dopants due to the capture of the associated electrons by dopant midgap states and the weakening of Al-O bonds. These oxygen vacancies and vacancy clusters also bind significantly to the dopant, thereby serving as preferential sites and building blocks in the formation of conducting paths. Throughout this work, we validate this theory experimentally by implanting different dopants over a range of electronegativities in devices made of multiple alternating layers of Al 2 ⁢O 3 and WN and find superior repeatability and yield with highly electronegative metals, Au, Pt, and Pd. These devices also exhibit a gradual SET transition, enabling multibit switching that is desirable for analog computing.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Multi-beam resin curing system and method for whole-volume additive manufacturing

A multi-beam volumetric resin curing system and method for whole-volume additive manufacturing of an object includes a bath containing a photosensitive resin, a light source for producing a light beam, and a spatial light modulator which produces a phase- or intensity-modulated light beam by impressing a phase profile or intensity profile of an image onto a light beam received from the light source. The system and method also include projection optics which then produces multiple sub-image beams from the modulated light beam which are projected to intersect each other in the photosensitive resin to cure select volumetric regions of the resin in a whole-volume three-dimensional pattern representing the object.

Shusteff, Maxim↗