Hello,

Just to echo what's been discussed--I've played with a ~9000 angstrom thick
heater (Ti-Pt-Au evaporated on LSN and with Au being the primary
current-carrying layer at 8000 angstrom thick). I power-cycled it within
15VDC; and over time, little tiny "white" dots were observed on the heater
surface. Then I fried it by juicing it with 18VDC. The damaged zone turned
into a "white belt," and I looked at it under an SEM and found that there
were a lot of little "islands" formed where there used to be smooth
continuous gold. But the thing is that I couldn't tell whether they were
islands or valleys. So I really don't know whether it's gold that's beaded
up, or silicon has diffused to the top and vice versa for the gold.

Does anyone have any insight into this, or have come across any relating
paper? I have kept the pictures, but I'm not sure if we're supposed to
attach anything with our email to the listserve.

joyce

>Allow me to add to my original answer.  I am quite sure this is what is
>happening, though I am a little surprised that it would occur for a 1000
>angstrom film.  Gurvinderjit- are you sure of this thickness?
>
>I used to make a form of tunneling sensor just this way- depositing 300-500
>angstrom gold films on a glass slide, then heating the suface until the
>uniform gold film broke apart and migrated to form discrete but closely
>spaced "islands".  I then filled the space in between with one of several
>organic semiconducting films to enhance the tunneling efficiency as they
>were exposed to various VOC's.