Lee,

I have to agree with Mike, and add that melting point has
nothing to do with it since you are evaporating metal.

Titanium (8893 J/g) has a significantly higher latent heat
of evaporation than palladium (3398 J/g), the energy needed
to go from liquid to vapor.

Titanium (21.9W/mK) should be easier to evaporate than gold
(318W/mK) because it has the lower thermal conductivity. The
entire bulk of gold must melt first before it will
evaporate, whereas the titanium can have a puddle of melt on
top of the bulk.

At least you can recognize different emission current
values. I have an uncalibrated analog meter that reads the
same low number for everything!

Jeff


---- Original message ----
>Date: Tue, 07 Dec 2004 12:31:58 -0500
>From: "Michael D Martin" 
>Subject: Re: [mems-talk] [q]e-beam evaporator power
>To: 
>
>Hi Lee,
>  I would suspect that the thermal conductivity and
electrical
>resistivity of the materials would influence the deposition
rates. In
>case you use different  boats for holding the tagets,
material
>differences may also have an impact on the net thermal
conductivity.
>
>-Mike
>
>
>
>
>>>> lsjun@phya.snu.ac.kr 12/6/2004 5:34:32 PM >>>
>Dear members,
>
>I'm a graduate student of Physics.
>I would like to know about the mechanism of power in the
electron beam
>evaporator.
>We made a simple e-beam evaporator for metallization (Ti,
Pt, and Pd)
>using 1mm diameter metal rod in the lab.
>
>As you may know well, the emission current determine the
power in the
>evaporator.
>Strangely, I found the emission current of Ti is higher
than that of Pd
>to get the same evaporating rate,
>even though the melting point of Ti is less than that of
Pd .
>In my experience in MEMS instruments, the emssion current
of Ti is very
>lower than that of Au.
>Could you how to explain this fact?
>
>As another question, I would like to know the behavior of
metal rod
>(source).
>In the Pt case, the droplet was formed on top of the rod in
>evaporating.
>But Ti rod was bent after evaporating and Pd was formed the
needle
>shape like SPM tip.
>Does anyone know about these things?
>
>Thank you in advance.
>
>Lee
>
>
>
>
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