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September 2011

April 2011

Thursday afternoon

I briefly dropped by some talks about thermoelectric energy harvesting. I was excepting the talk by Dr. Ramesh about STO. But his student showed up instead. The talk was good and clear, no disappointment for me. Another talk was offered by Sandia national lab about TE materials aging experiement. Commercial devices were annealed at 250C for 7days. It is a interesting dig-in point. I am not sure if 7 days are enough for any significant change at such a low temperature. I hardly picked up any final conclusion at this point, and I am expecting their further experiments and results. Nice sunshine outside, don't forget to go out and get some fresh air. See you at the poster session tonight.

Nonvolatile Memory Devices

Nonvolatile memory devices (Q) is a fascinating symposium. It's amazing how many different ways there are to electrically encode information in a material, and equally amazing how many are close to beating flash NAND (and each other). The technologies discussed this week include:

  • FeRAM (Ferroelectric)
  • ReRAM (Resistive)
  • MRAM (Magnetic)
  • Phase Change Memory (Also resistive, usually)
  • Polymer Memories (Often ferroelectric or resistive)
  • Charge Trapping Memory
  • MEMS Memory (Capacitive and resistive are two options)

What makes many of these technologies particularly interesting and different from flash NAND is that electron positions aren't the thing encoding the 1s and 0s. Other degrees of freedom like nuclei position (crystal structure) and electron spin (magnetism) come into play.

One of the most interesting talks today was on MEMS memory by Professor Tsu-Jae King Liu from UC Berkeley. She talked about using nano-cantilevers as physical switches. It turns out this approach has some compelling advantages and is even compatible with today's CMOS. However, there may be problems scaling down the cantilevers, which will need to become stiffer and stiffer as they get smaller and smaller. I also wonder about how valid some assumptions will be as cantilevers scale down to just a handful of atoms thick. Nonetheless, two start-ups are already trying to commercialize MEMS memory, which they hope will be the next generation of nonvolatile memory. Time will tell!


By metascience I don't mean metamaterials: I mean thinking about how science works as a human enterprise. As you can probably tell from my other posts, I often think about this issue. This morning, I had the great privilege of speaking with a distinguished scientist at one of our national laboratories about how science really works in his setting. He shared both the idealism of wanting to do science in the national and public interest, and the reality of bureaucracy, proposal writing, dealing with management, etc. I started thinking: is there anything that can be done about this situation? How could I help? Trying to change the way science works for the better is something I'm passionate about.

A Morning of Multiferroics!

2011-04-28 11.26.21

Manel Bibes speaks about giant electric field control of spin-waves. I'm still not sure what the "giant" refers to, but it was really interesting.


2011-04-28 11.41.33

Ju Choi speaks about synthesis using radical atomic layer deposition.


2011-04-28 11.44.04
Ignasi Fina speaks about tuning ferroelectricity with magnetism!

Thursday morning talks

I spent the whole morning in heat transfer sessions. The thermal conductivity NID measurement talk by UCSC Ali Shakouri's group was very interesting. Then the talk about thermal conductivity approach to measure phonon mfp talk was presented in another session. Usually, it's hard to extract the mfp term. Researchers from Gang Chen's group demostrate the transient thermoreflectance phonon mfp measurement for Si. This will enhance the understanding of phonon transportation, and lead to heat transfer control.

There are more talks in the energy harvest session this afternoon. I am expecting to see more new materials systems developed for thermal energy harvesting.

Silicon Valley

Well, SF isn't technically in Silicon Valley, but it's not too far up the road and it's also a hotbed of tech innovation. While walking back to my hotel from the Caltrain station, I happened to walk past the headquarters for this very blog platform on Fourth St.

Silicon Valley

Scientists like freebies

I just want to compliment MRS for offering free coffee. It's a nice touch, and probably adds a lot more value in people's minds than it costs to provide. Also, the Seattle's Best dark roast is delish (who knew)? I took this picture of people swarming the coffee table like moths to a flame. I like to think that, even years after grad school, researchers never lose their conditioning to take advantage of free food and drink whenever possible.

Scientists like freebies

First-time talk in MRS

This afternoon, I had my first time talk in MRS about nanowire thermoelectrics. It ran smoothly. I was a bit worried about the timing and questions the audiences may have due to the high density of information in the slides. At the end, I found myself kept a very fast pace, and all the points had been delivered more or less. I feel good for the talk. Because usually, when I am nervous or in a hurry, I will skip stuff. There are still things can be improved. I think will come up with a better talk for the next MRS meeting.

Btw, University chapter is trying to bring in more univeristies' paticipation. Nano-day, K12 education, nano student convocation, on all kinds of interesting activities MRS university chapter can help.

Tomorrow also has lots of nice talks like previous days. See you in West Moscone center!

Commuting Back to Berkeley

2011-04-27 17.06.23

With the ceilings so high, I'm not sure the emergency exit signs will help anyone evacuate.


2011-04-27 18.00.05
Waiting for BART


2011-04-27 17.38.31
Riding BART


2011-04-27 18.01.44


2011-04-27 18.03.37
Downtown Berkeley. Berkeley is famous for its food, though the fusion Mexican/Indian/Pakistani taqueria on this streetcorner may not make the top 100 showcase.


2011-04-27 18.05.25

This building, under construction ever since I've been at Berkeley (granted, less than one year), will be UC Berkeley's new Helios Energy Research Facility.


2011-04-27 18.05.00
 Bums are common in Berkeley.


2011-04-27 18.11.26
But so are bikes!


2011-04-27 07.38.26
My neighborhood, a half mile from both the BART station and campus.