question regarding ?tiny/ small partial ( j ) scanner depoling

posted on Thu, Jan 7 2010 4:44 PM

rated by 0 users

I have an older J scanner, that unfortunately I left powered on for some
modest amount of minutes without the PC connected to the nanoscope 3
controller. I kept hearing buzzing and soon realized something was wrong. It
is clear from some online docs at a few select websites this was a mistake
and potentially causes depoling of the piezos. I did not suffer catastophic
depoling since only (very) small scan sizes on my J scanner are degraded (
drifty ) where they otherwise prior to this incident were stable as a rock

I read here http://www.mechmat.caltech.edu/~kaushik/park/2-1-0.htm

"Occasional use of the scanner will help maintain the scanner's
polarization. The voltage applied to enact the scanning motion realigns the
stray dipoles that relax into random orientation. If the scanner is not
repoled by regular use, a significant fraction of the dipoles will begin to
randomize (depolarize or depole) again over a period of weeks. Depoling is
accelerated markedly if the scanner is subjected to temperatures above
150°C. This means that if you want to add a heated stage to your SPM, you
must isolate it thermally from the scanner. (The Curie temperature for PZT
materials is about 150°C.) "

My inferred interpretation is that particular scan voltage offset treatment
of prolonged duration might actually help mitigate the slight damage I
incurred.

I an curious as to the proper configuration ( possibly with other scanner
segment disconnects via the breakout box ) that can at least partially
mitigate the likely modest depoling I incurred.

The only image distortion / noise I see is for a 90 um J scanner, is just
for scan areas below 200-300nm, where prior to this unfortunate incident, my
J scanner performed flawlessly at these and smaller scan areas / ranges.

My intuition is that a particular sequence of scanner electrode disconnects,
with corresponding static offset voltage treatments of reasonable duration
of minutes to hours? even if done at ambient, is likely to at least
partially correct for the modest depoling I incurred for the 2-3 minutes of
scanner "buzzing" from random scan voltages without the PC connected.

Clearly after such a hypothetical "remedial" scanner treatment I will have
to recalibrate the scanner ( which I am up for anyways - pretty easy ), and
clearly such a method will only "potentially" be useful for the very modest
depoling such as I have experienced.

Since I have a breakout box, sequential disconnects of appropriate scanner
drive signals ( here to be used for static voltage treatments at ambient
temperature ) are easy, hence I think what I describe is indeed conceivable,
I just which to know the correct offset / polarity for how to do this (
which is not recommended for the average or new user )

I'd be curious as to other (advanced) users' experience in this type of
issue of tiny partial depoling ( of J scanners )

I am pretty certain the limited depoling observed is "treatable" with an
ambient "repoling if done with correct polarity and sequence ( scanner
segment connects / disconnects ) to treat the appropriate scanner segments
individually?

Thanks !