This is the worst /. article *summary* that I've read this week. TFA addresses phase-change materials (PCM)-based memory only. This is the self-same stuff used in writable DVDs, and has some very cool properties.
In the above summary, "Faster than other solutions currently available" refers specifically to PCM-based memory. The durability of PCM memory is one big plus -- all those sci-fi plot twists from cosmic ray induced bit-flips in charge-dependent memory? Yeah, not a problem here.
TFA itself is a really neat little paper. It's in Science, which indicates that some reviewers somewhere thought it both important and well-done. It's surprisingly readable, too, which is a little unusual for these sorts of papers.
These folks were clearly thinking about Fab-type high volume / high yield questions. For example, the "quality" of the carbon nanotubes (CNTs) isn't important. They're just an easily-broken conductor. Clearly this isn't ready for prime-time, but they didn't just make 1 device, test it, and publish. They made at least 100, while varying conditions.
From TFA's Supporting Online Material:
" In order to create the CNT nanogaps, we performed electrical breakdown of CNTs both in
ambient air and under Ar flow. We have also cut CNTs with AFM manipulation, but the elec-
trical breakdowns offered a much faster route to obtain a wide range of nanogaps (Fig. 4). Of
course, while the CNT breakdown method is extremely useful here, it would not be the preferred
route for obtaining nanogaps in a more scalable manufacturing environment. Nevertheless, we
believe it is useful to present some observations associated with this technique here.
First, we note that CNT breakdowns under Ar flow were done by flowing Ar (which is
heavier than air) from a small nozzle over the entire test chip while probing. Thus, some dimi-
nished amount of oxygen was still available for CNT breakdown, unlike the breakdowns per-
formed in vacuum in the second panel of Fig. 2C of Ref. (1). There, the CNT break in vacuum
could lead to SiO2 damage, which was not seen here either in ambient air or under Ar flow.
Second, we found that nanogaps formed in Ar are always smaller (always
We report additional statistics for all devices measured by AFM in Fig. S7. We find no clear
dependence between nanogap size and CNT diameter (Fig. S7A). In a sense, this is encouraging
because it suggests that tight control of CNT electrode diameter may not be necessary to make
very low power devices. Our simulations (Figs. S3 and S4) also suggest this is the case, because
the resistance of the GST bit always dominates that of the CNT (both in the a- and c-GST phase),
thus rendering variability in the CNT of less importance. This fact could be important for mass
production of such electronics where some amount of CNT variability could be tolerated."
